RESUMEN
T cell engaging bispecific antibodies (TCBs) have recently become significant in cancer treatment. In this study we developed MSLN490, a novel TCB designed to target mesothelin (MSLN), a glycosylphosphatidylinositol (GPI)-linked glycoprotein highly expressed in various cancers, and evaluated its efficacy against solid tumors. CDR walking and phage display techniques were used to improve affinity of the parental antibody M912, resulting in a pool of antibodies with different affinities to MSLN. From this pool, various bispecific antibodies (BsAbs) were assembled. Notably, MSLN490 with its IgG-[L]-scFv structure displayed remarkable anti-tumor activity against MSLN-expressing tumors (EC50: 0.16 pM in HT-29-hMSLN cells). Furthermore, MSLN490 remained effective even in the presence of non-membrane-anchored MSLN (soluble MSLN). Moreover, the anti-tumor activity of MSLN490 was enhanced when combined with either Atezolizumab or TAA × CD28 BsAbs. Notably, a synergistic effect was observed between MSLN490 and paclitaxel, as paclitaxel disrupted the immunosuppressive microenvironment within solid tumors, enhancing immune cells infiltration and improved anti-tumor efficacy. Overall, MSLN490 exhibits robust anti-tumor activity, resilience to soluble MSLN interference, and enhanced anti-tumor effects when combined with other therapies, offering a promising future for the treatment of a variety of solid tumors. This study provides a strong foundation for further exploration of MSLN490's clinical potential.
RESUMEN
The geometry of retinal layers is an important imaging feature for the diagnosis of some ophthalmic diseases. In recent years, retinal layer segmentation methods for optical coherence tomography (OCT) images have emerged one after another, and huge progress has been achieved. However, challenges due to interference factors such as noise, blurring, fundus effusion, and tissue artifacts remain in existing methods, primarily manifesting as intra-layer false positives and inter-layer boundary deviation. To solve these problems, we propose a method called Tightly combined Cross-Convolution and Transformer with Boundary regression and feature Polarization (TCCT-BP). This method uses a hybrid architecture of CNN and lightweight Transformer to improve the perception of retinal layers. In addition, a feature grouping and sampling method and the corresponding polarization loss function are designed to maximize the differentiation of the feature vectors of different retinal layers, and a boundary regression loss function is devised to constrain the retinal boundary distribution for a better fit to the ground truth. Extensive experiments on four benchmark datasets demonstrate that the proposed method achieves state-of-the-art performance in dealing with problems of false positives and boundary distortion. The proposed method ranked first in the OCT Layer Segmentation task of GOALS challenge held by MICCAI 2022. The source code is available at https://www.github.com/tyb311/TCCT.
Asunto(s)
Algoritmos , Tomografía de Coherencia Óptica , Tomografía de Coherencia Óptica/métodos , Retina/diagnóstico por imagen , Fondo de Ojo , Interpretación de Imagen Asistida por Computador/métodosRESUMEN
Objectives: This study aimed to investigate the matching degree between the donated supply and demand, clinical characteristics of both donors and recipients, along with the operation cost. Methods: From January 1, 2018 to December 31, 2021, the data on human milk donation and usage, the clinical characteristics of donors and recipients, and the cost of each operating center were collected from the Manual Donation Registration Form and Information Management System of the selected human milk bank. Results: During the four years that the human milk bank was in operation, the volume of donated milk was slightly greater than the volume of consumed milk. A total of 1364 donors donated 2434.63 liters of qualified human milk, for RMB 1,791,000 (USD 257, 202), ie, RMB 385.3 (USD 55.3)/L; 97.8% of the donors were preterm puerperae, and 59% of the donors donated between 1 week and 1 month after delivery. All recipients were preterm infants and received donated human milk for a duration of 9.4 days on average. During the four years of operation, the proportion of donors who had previously received donated milk among all donors showed an overall increasing trend, while the incidence of NEC in preterm infants gradually decreased. Conclusions: The increasingly optimized structure of donors, the more economical operation, and the fact that the use of donated milk may not affect breastfeeding of the recipients have made it a human milk bank operation mode worthy of promotion.
RESUMEN
The continuous emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants poses challenges to the effectiveness of neutralizing antibodies. Rational design of antibody cocktails is a realizable approach addressing viral immune evasion. However, evaluating the breadth of antibody cocktails is essential for understanding the development potential. Here, based on a replication competent vesicular stomatitis virus model that incorporates the spike of SARS-CoV-2 (VSV-SARS-CoV-2), we evaluated the breadth of a number of antibody cocktails consisting of monoclonal antibodies and bispecific antibodies by long-term passaging the virus in the presence of the cocktails. Results from over two-month passaging of the virus showed that 9E12 + 10D4 + 2G1 and 7B9-9D11 + 2G1 from these cocktails were highly resistant to random mutation, and there was no breakthrough after 30 rounds of passaging. As a control, antibody REGN10933 was broken through in the third passage. Next generation sequencing was performed and several critical mutations related to viral evasion were identified. These mutations caused a decrease in neutralization efficiency, but the reduced replication rate and ACE2 susceptibility of the mutant virus suggested that they might not have the potential to become epidemic strains. The 9E12 + 10D4 + 2G1 and 7B9-9D11 + 2G1 cocktails that picked from the VSV-SARS-CoV-2 system efficiently neutralized all current variants of concern and variants of interest including the most recent variants Delta and Omicron, as well as SARS-CoV-1. Our results highlight the feasibility of using the VSV-SARS-CoV-2 system to develop SARS-CoV-2 antibody cocktails and provide a reference for the clinical selection of therapeutic strategies to address the mutational escape of SARS-CoV-2.
Asunto(s)
Anticuerpos Biespecíficos , COVID-19 , Humanos , SARS-CoV-2 , Terapéutica Combinada de Anticuerpos , Pruebas de Neutralización , Anticuerpos Biespecíficos/uso terapéutico , Anticuerpos NeutralizantesRESUMEN
BACKGROUND: This study evaluated the effects of less invasive surfactant administration (LISA) and intubation-surfactant-extubation (InSurE) on bronchopulmonary dysplasia (BPD) in preterm infants with respiratory distress syndrome (RDS). METHODS: Neonates with respiratory distress syndrome requiring surfactant, with gestational age < 32 weeks and birth weight < 1500 g admitted to our neonatal intensive care unit from January 2018 to December 2019, were retrospectively analyzed. LISA and InSurE were used independently. The incidence of BPD at 36 weeks postmenstrual age, pre-discharge mortality, and need for mechanical ventilation (MV) within 72 h of birth were compared between LISA and InSurE group. Secondary outcomes including necrotizing enterocolitis requiring surgery, retinopathy of prematurity ≥ stage 3, patent ductus arteriosus requiring medical therapy or surgery, and length of hospitalization were analyzed. RESULTS: Among the 148 included neonates, there were 46 and 102 infants in LISA group and InSurE group, respectively. There were no significant differences in BPD incidence, the severity of BPD at 36 weeks postmenstrual age, and the rate of MV within the first 72 h after birth between the two groups (P > 0.05, respectively). The incidences of necrotizing enterocolitis requiring surgery, retinopathy of prematurity ≥ stage 3, patent ductus arteriosus requiring medical therapy or surgery, and length of hospitalization did not differ significantly between the two groups (P > 0.05, respectively). CONCLUSIONS: For surfactant administration among preterm infants with respiratory distress syndrome, LISA did not decrease bronchopulmonary dysplasia and severity of BPD at 36 weeks postmenstrual age. The benefits of LISA would require further evaluations.
Asunto(s)
Displasia Broncopulmonar , Conducto Arterioso Permeable , Enterocolitis Necrotizante , Surfactantes Pulmonares , Síndrome de Dificultad Respiratoria del Recién Nacido , Retinopatía de la Prematuridad , Lactante , Recién Nacido , Humanos , Estudios Retrospectivos , Recien Nacido Prematuro , Displasia Broncopulmonar/epidemiología , Displasia Broncopulmonar/terapia , Extubación Traqueal , Enterocolitis Necrotizante/epidemiología , Tensoactivos/uso terapéutico , Surfactantes Pulmonares/uso terapéutico , Síndrome de Dificultad Respiratoria del Recién Nacido/terapia , Respiración Artificial , Intubación Intratraqueal , Recién Nacido de muy Bajo PesoRESUMEN
Astragalus polysaccharide(APS), one of the main active components of Astragali Radix, plays an anti-tumor effect by regulating the inflammatory microenvironment of tumors. Exosomes are small extracellular vesicles with a diameter ranging from 50 to 200 nm and carry several biological components from parental cells such as nucleic acids and proteins. When combined with recipient cells, they play an important role in intercellular communication and immune response. In this study, exosomes released from H460 cells at the inflammatory state or with APS addition activated by Toll-like receptor 4(TLR4) were extracted by ultracentrifugation and characterized by Western blot, transmission electron microscopy, and nanoparticle tracking analysis. The exosomal proteins derived from H460 cells in the three groups were further analyzed by label-free proteomics, and 897, 800, and 911 proteins were identified in the three groups(Con, LPS, and APS groups), 88% of which belonged to the ExoCarta exosome protein database. Difference statistical analysis showed that the expression of 111 proteins was changed in the LPS group and the APS group(P<0.05). The biological information analysis of the differential proteins was carried out. The molecular functions, biological processes, and signaling pathways related to the differential proteins mainly involved viral processes, protein binding, and bacterial invasion of proteasome and epithelial cells. Key differential proteins mainly included plasminogen activator inhibitor-1, laminin α5, laminin α1, and CD44, indicating that tumor cells underwent systemic changes in different states and were reflected in exosomes in the inflammatory microenvironment. The analysis results also suggested that APS might affect the inflammatory microenvironment through the TLR4/MyD88/NF-κB signaling pathway or the regulation of the extracellular matrix. This study is conducive to a better understanding of the mechanism of tumor development in the inflammatory state and the exploration of the anti-inflammatory effect of APS at the exosome level.
Asunto(s)
Planta del Astrágalo , Exosomas , Neoplasias Pulmonares , Humanos , Exosomas/metabolismo , Proteómica , Receptor Toll-Like 4/genética , Receptor Toll-Like 4/metabolismo , Lipopolisacáridos , Planta del Astrágalo/química , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Polisacáridos/farmacología , Polisacáridos/metabolismo , Microambiente TumoralRESUMEN
The outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV) has become a most challenging health emergency. Owing to rigorous quarantine and control measures taken in China, routine neonatal health surveillance and follow-up have become challenging. Without follow-up surveillance, some rapid and progressive newborn diseases, such as bilirubin encephalopathy, may be ignored. The characteristics of onset age of kernicterus suggest that monitoring of bilirubin level at home provides a useful way to alert hospital visits and to prevent the development of extremely hyperbilirubinemia. Therefore, we developed an online follow-up program for convenient monitoring of bilirubin level of newborns that is based on our practical experiences. The aim is to make our management strategies of neonatal jaundice tailored to the infection prevention and control during the COVID-19 epidemic.
Asunto(s)
Cuidados Posteriores/métodos , Bilirrubina/sangre , Infecciones por Coronavirus , Ictericia Neonatal/sangre , Ictericia Neonatal/terapia , Aplicaciones Móviles , Pandemias , Neumonía Viral , COVID-19 , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/prevención & control , Brotes de Enfermedades , Humanos , Recién Nacido , Monitoreo Fisiológico , Pandemias/prevención & control , Neumonía Viral/epidemiología , Neumonía Viral/prevención & controlRESUMEN
Regenerating gene 3α (Reg3α) protein is a trophic factor that stimulates cell and tissue proliferation, neogenesis and also acts against apoptosis and necrosis. In order to explore the potential roles of recombinant Reg3α (rReg3α), we produced a mature rReg3α polypeptide for direct administration in l-arginine (L-Arg) induced acute pancreatitis (AP) in mice. Our results showed that rReg3α stimulated cell proliferation through Erk1/2 and p38 phosphorylation and also cyclin D1 upregulation mediated by Akt/ATF-2 signaling. Moreover, rReg3α administration significantly reduced the pancreatic damage caused by L-Arg injection, as shown in histological examination and serum amylase, lipase and C-reactive protein (CRP) assays. Not only acinar cell necrosis but also apoptosis found in the pancreas of AP mice were alleviated by rReg3α. Finally, upregulated Bcl-2 and Bcl-xL and suppressed poly (ADP-ribose) synthetase/polymerase (PARP) levels were detected as being relevant to the mechanism of rReg3α protection. We therefore conclude that rReg3α acts as a protective polypeptide against AP in mice by enhancing Bcl-2 and Bcl-xL expressions and suppressing PARP level.
Asunto(s)
Antígenos de Neoplasias/administración & dosificación , Arginina/efectos adversos , Biomarcadores de Tumor/administración & dosificación , Lectinas Tipo C/administración & dosificación , Pancreatitis/prevención & control , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Células Acinares/efectos de los fármacos , Animales , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Antígenos de Neoplasias/farmacología , Apoptosis/efectos de los fármacos , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Biomarcadores de Tumor/farmacología , Línea Celular , Proliferación Celular , Modelos Animales de Enfermedad , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Ratones , Pancreatitis/inducido químicamente , Pancreatitis/patología , Proteínas Asociadas a Pancreatitis , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacología , Transducción de Señal/efectos de los fármacosRESUMEN
BACKGROUND: To compare neonatal mortality and neurodevelopmental outcomes at two years of age in very low birth weight infants (≤1500 g) born by cesarean with those by vaginal delivery. METHODS: In this retrospective, case-control study, we evaluated neonatal mortality, medical conditions and neurodevelopmental outcomes at two years of corrected age in 710 very low birth weight (VLBW) infants born between January 2005 and December 2010. Of the 710 infants, 351 were born by the cesarean and 359/710 by vaginal route. RESULTS: There were no significant differences in neonatal mortality between the cesarean delivery group and vaginal delivery group [56/351 (15.9%) vs. 71/359 (19.8%), P=0.20]. VLBW infants delivered by the cesarean procedure had a higher incidence of respiratory distress syndrome than those born by the vaginal route [221/351 (63.0%) vs. 178/359 (49.6%), P<0.001]. There were no differences in other neonatal morbidities, including intraventricular hemorrhage [126/351 (35.9%) vs. 134/359 (37.3%), P=0.69], bronchopulmonary dysplasia [39/351 (11%) vs. 31/359 (8.6%), P=0.38] and necrotising enterocolitis [40/351 (11.4%) vs. 32/359 (8.9%), P=0.32] between the two groups. The incidence of poor neurodevelopment after cesarean delivery was similar to that after vaginal delivery [105/351 (29.9) vs. 104/359 (29.0%), P=0.78]. CONCLUSIONS: In neither neurodevelopment nor neonatal mortality did cesarean birth offered significant advantages to VLBW infants. Moreover, the operation might be associated with an increased risk of respiratory distress syndrome for VLBW infants. The mode of delivery of VLBW infants should be largely based on obstetric indications and maternal considerations rather than perceived better outcomes for the neonate.
Asunto(s)
Cesárea/estadística & datos numéricos , Parto Obstétrico/estadística & datos numéricos , Discapacidades del Desarrollo/epidemiología , Mortalidad Infantil , Recién Nacido de muy Bajo Peso , Estudios de Casos y Controles , Hemorragia Cerebral/epidemiología , Cesárea/mortalidad , Preescolar , China/epidemiología , Parto Obstétrico/mortalidad , Discapacidades del Desarrollo/mortalidad , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Embarazo , Síndrome de Dificultad Respiratoria del Recién Nacido/epidemiología , Estudios Retrospectivos , Medición de Riesgo , Factores de RiesgoRESUMEN
Comparative analysis of variable region ORF14/15 genes of white spot syndrome virus (WSSV) genome in Guangxi Penaeus vannamei (P. vannamei) could provide useful information for the evaluation of genetic diversity and genetic evolutionary relationship among WSSV isolates from Guangxi, China and other places. Based on geographical and temporal considerations, 40 WSSV-positive P. vannamei samples were collected during the period between May 2010 and July 2013 from Beihai, Qinzhou, and Fangchenggang, which were the main P. vannamei production areas in Guangxi, and the variable region ORF14/15 genes of the WSSV genome from all infected samples were amplified by PCR and then subjected to cloning and sequence analysis. Pairwise and multiple alignment analysis was then conducted to evaluate the degree of genetic divergence between different strains. The variable region ORF14/15 genes from 25 of 40 WSSV positive samples were successfully cloned and sequenced; among the ORF14/15 genes of 25 WSSV-positive strains, 22 was 619 bp in length and 3 was 620 bp. All the 25 Guangxi strains carried a 5949-bp deletion in the ORF14/15 region relative to TH-96-II, which has the longest nucleotide sequence in this region; the deletion of Guangxi strains occurred in the middle region of ORF14/15 gene, with only 190 bp and 429 bp/ 430 bp at 5' and 3' ends, respectively, which were coincident with WSSV-IN-05-I in deletion length and position. Sixteen of 25 Guangxi strains had completely identical nucleotide sequences in the variable re gion, and the homology between other strains also exceeded 97.9%. There were single nucleotide substi tution, deletion, and insertion in the ORF14/15 region of Guangxi strains compared with other strains in GenBank. In the phylogenetic tree based on WSSV variable region ORF14/15, the Guangxi strains were closely related and formed a separate branch with Indian strain IN-05-I, but far from other strains in GenBank. The ORF14/15 gene of WSSV isolates in cultured P. vannamei in Guangxi has a large deletion in the middle of the variable region, and the Guangxi WSSV strains show no significant spatio-temporal differences; the Guangxi strains are closer in genetics to Indian strain IN-05-I than other strains in GenBank.
Asunto(s)
Genómica , Penaeidae/virología , Virus del Síndrome de la Mancha Blanca 1/genética , Animales , China , Clonación Molecular , Evolución Molecular , Genoma Viral/genética , FilogeniaRESUMEN
OBJECTIVE: To review the health status of mothers undergoing in vitro fertilization-embryo transfer (IVF) and their offspring. METHODS: Health status of 210 IVF mothers and offspring performed from January 1, 2001 through December 31, 2002 was compared with that of those who conceived naturally retrospectively. RESULT: A significant differences were found in rates of multiple births, hypertensive disorders in pregnancy,cesarean section, preterm delivery,low (and very low) birth weight infant,malformation(33.33 % with compared 1.72 %, 10.87 % with compared 4.59 %, 89.85 % with compared 65.57 %, 24.64 % with compared 6.27 %, 25.68 % with compared 8.23 %, 3.83 % with compared 1.17 %, all P<0.01) between IVF and those conceived naturally. The rates of hypertensive disorders in pregnancy,preterm delivery, low (and very low) birth weight infant were related to the rate of multiple births OR. 95 %CI were 3.49, 1.16-10.50; 13.65, 5.39-34.58; 14.91, 5.53-40.17; respectively. There was no statistical difference in neonatal outcome between normal IVF and intra-cytop-lasmic sperm injection (P>0.05); no difference in height and weight between full-term and preterm (P>0.05). CONCLUSION: Assisted reproductive technologies increase multiple births rate, resulting in high rates of hypertensive disorders, preterm delivery, low (and very low) birth weight infant.
Asunto(s)
Transferencia de Embrión , Fertilización In Vitro , Estado de Salud , Hipertensión Inducida en el Embarazo/epidemiología , Nacimiento Prematuro/epidemiología , Adulto , Cesárea/estadística & datos numéricos , China/epidemiología , Femenino , Humanos , Progenie de Nacimiento Múltiple , Embarazo , Estudios RetrospectivosRESUMEN
Midkine is a heparin-binding growth factor, which plays important roles in the regulation of cell growth and differentiation. The non-tagged recombinant human midkine (rhMK) is therefore required to facilitate its functional studies of this important growth factor. In the present work, rhMK was expressed in Escherichia coli (E. coli) BL21 (DE3). The expression of midkine was efficiently induced by isopropyl-beta-D-thiogalactopyranoside (IPTG). After sonication, midkine was recovered in an insoluble form, and was dissolved in guanidine hydrochloride buffer. Renaturation of the denatured protein was carried out in the defined protein refolding buffer, and the refolded protein was purified using S-Sepharose ion-exchange chromatography. The final preparation of the rhMK was greater than 98% pure as measured by sodium dodecylsulfate-polyacrylamid gel electrophoresis (SDS-PAGE) and reverse phase high performance liquid chromatography (RP-HPLC). The purified rhMK enhanced the proliferation of NIH3T3 cells.
Asunto(s)
Citocinas/biosíntesis , Proteínas Recombinantes/biosíntesis , Animales , Secuencia de Bases , Proliferación Celular/efectos de los fármacos , Citocinas/genética , Citocinas/aislamiento & purificación , Citocinas/farmacología , Escherichia coli/genética , Humanos , Ratones , Midkina , Datos de Secuencia Molecular , Células 3T3 NIH , Proteínas Recombinantes/aislamiento & purificaciónRESUMEN
OBJECTIVE: To find out optional resuscitation gas for asphyxiated newborn infants based on a systemic review of the published studies that compared the effects of resuscitation of asphyxiated newborn infants with room air or pure oxygen. METHODS: Inclusion criteria were randomized or pseudo-randomized studies of asphyxiated newborn infants resuscitated with room air or pure oxygen. The studies published between Jan. 1966 and June. 2005 were searched in PubMed/EMBASE/the Cochrane library databases. All identified studies that fulfilled our inclusion criteria were included. We did a systemic review and a meta-analysis of studies that compared parameters of efficacy, such as mortality, incidence of hypoxic ischemic encephalopathy (HIE) and the rate of resuscitation failure of newborn infants resuscitated with room air or pure oxygen. RESULTS: Six identified studies were included, in which 988 infants were resuscitated with room air and 952 infants with pure oxygen. The mortality of asphyxiated newborn infants within the first week was 8.7% versus 13.4% in room air and pure oxygen groups, respectively, OR = 0.64, 95% CI 0.44 - 0.94. In 5 of the 6 studies, the mortality of term asphyxiated newborn infants was 5.9% versus 9.8% in room air and pure oxygen groups, OR = 0.59, 95% CI 0.40 - 0.87. The result for premature asphyxiated newborn infants was similar. In 4 studies, the incidence of moderate to severe neonatal HIE was 17.5% versus 20.1% in room air and pure oxygen groups, respectively, OR = 0.91, 95% CI 0.68 - 1.21. In 3 studies, the rate of resuscitation failure was 26.9% versus 29.1% in room air and pure oxygen groups, respectively, OR = 0.92, 95% CI 0.70 - 1.19. CONCLUSION: The systemic review and the meta-analysis demonstrated that the mortality of asphyxiated newborn infants was significantly lower when resuscitated with room air, and no significant differences were found in the incidence of neonatal HIE and the rate of resuscitation failure. However, this conclusion should be used cautiously because of the limited number of studies.
Asunto(s)
Asfixia Neonatal/terapia , Terapia por Inhalación de Oxígeno , Oxígeno/uso terapéutico , Resucitación/métodos , Aire , Asfixia Neonatal/mortalidad , Humanos , Recién Nacido , Neonatología , Resultado del TratamientoRESUMEN
A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry.
RESUMEN
An efficient method for the construction of two carbon-carbon bonds in a regio- and stereoselective fashion via palladium-catalyzed assembling of allenes, organic halides, and arylboronic acids is described. Organic halides (RI = C(6)H(5)I, o-, m-, and p-CH(3)OC(6)H(4)I, p-C(2)H(5)OCOC(6)H(4)I, p-CH(3)COC(6)H(4)I, p-CH(3)C(6)H(4)I, p-CH(3)C(6)H(4)Br, p-CH(3)C(6)H(4)Cl, p-NO(2)C(6)H(4)I, p-NO(2)C(6)H(4)Br, p-NO(2)C(6)H(4)Cl, p-IC(6)H(4)Cl, 1-iodonaphthalene, 2-iodothiophene, 3-iodo-2-cyclopenten-1-one, 3-iodo-5,5-dimethyl-2-cyclohexen-1-one, C(6)Eta(5)(Br)C=CH(2) and ICH(2)CO(2)C(2)H(5)), and arylboronic acids (ArB(OH)(2), Ar = C(6)H(5), p-CH(3)OC(6)H(4), m-NO(2)C(6)H(4), p-FC(6)H(4), 1-C(10)H(7), and o-, m-, and p-CHOC(6)H(4)) undergo Suzuki-type three-component assembling with 1,1-dimethylallene to give the corresponding allylic derivatives, (CH(3))(2)=CRCH(2)Ar, in DMF at 70 degrees C in the presence of CsF using Pd(dba)(2) as the catalyst. Higher yields of products were obtained for aryl iodides than for the corresponding aryl bromides and chlorides. This three-component assembling is highly regioselective, with the organic group on halides adding to the middle carbon and the aryl group on arylboronic acids to the unsubstituted terminal carbon of allenes. Monosubstituted allenes 1b-e (cyclopentylallene, cyclohexylallene, tert-butylallene, and n-butylallene) also undergo similar assembling reaction with organic halides and arylboronic acids to afford the corresponding products 7a-i with high regio- and stereoselectivity. Based on the known palladium chemistry, a mechanism is proposed to account for the catalytic reaction and the stereochemistry.