Abnormal Michael Reaction: Condition-Dependent Product Distributions in the Michael Reaction of Monoalkyl-Substituted Malonates.

The abnormal Michael reaction reported by Thorpe and Michael in 1900, which involves the transfer of an activating group from a nucleophilic species to an α-carbon of the Michael acceptor in reaction with monosubstituted malonates, was revisited using prototypical substrates for both intramolecular and intermolecular reactions. In both reactions, condition-dependent product distributions were observed. Thus, under the conditions using NaHMDS or NaH in THF or Et2O, no formation of the abnormal Michael product was observed, and the major product was an apparent retrograde Michael reaction in the abnormal Michael product resulting from an elimination of a malonate anion with the migrated acyl group as a part of it. The use of a base capable of generating a proton source such as NaOEt resulted in formation of the abnormal Michael product in the intermolecular reaction, although the retrograde Michael product was still a major product. On the other hand, in the intramolecular reaction, the abnormal product was not detected under any conditions used. A plausible reaction mechanism in which the lower kinetic acidity of the malonate proton compared to the thermodynamic acidity plays a significant role has been proposed.

Cranial Reconstruction Using Antibiotic-Impregnated Calcium Phosphate Bone Cement With a Titanium Mesh Sheet.

BACKGROUND: The authors treated skin ulcer accompanied by cranial osteomyelitis using a combination of antibiotic-impregnated calcium phosphate bone cement (Biopex; Pentax, Tokyo, Japan) and a titanium mesh sheet (3D Mesh Plate; Bear Medic, Tokyo, Japan). METHOD: A 71-year-old male was treated with superficial temporal artery-middle cerebral artery bypass surgery for diffuse cerebral infarction and obstruction of the left internal carotid artery by a previous doctor. Skin necrosis and epidural abscess developed in the sutured region after surgery, and ulcer accompanied by temporal bone exposure remained. Thus, the patient transferred to our department. A bone defect formed by debridement and sequestrectomy was measured at 4.5 × 8 cm (30 cm). Methicillin-resistant Staphylococcus aureus was detected on wound culture test. Cranioplasty with a combination of calcium phosphate bone cement impregnated with teicoplanin, to which the causative bacteria showed high sensitivity, and a titanium mesh sheet and scalp reconstruction with a free rectus abdominis musculocutaneous flap were performed. RESULTS: As of 6 months after surgery, no infection has relapsed and no complication, such as resorption of the calcium phosphate bone cement and breakage of the titanium mesh sheet, was noted on postoperative computed tomography. CONCLUSION: The authors performed cranial reconstruction with a combination of teicoplanin-impregnated calcium phosphate bone cement and a titanium mesh sheet in a patient with Methicillin-resistant Staphylococcus aureus infection-induced skin ulcer accompanied by cranial osteomyelitis and achieved subsidence of infection. Drug-impregnated calcium phosphate bone cement has a problem with strength, but combination with a titanium mesh sheet as an auxiliary support material enables application to relatively extensive cranial full-thickness defects and it may be a useful treatment method.

Inhibitory effects of antibiofilm compound 1 against Staphylococcus aureus biofilms.

A novel benzimidazole molecule that was identified in a small-molecule screen and is known as antibiofilm compound 1 (ABC-1) has been found to prevent bacterial biofilm formation by multiple bacterial pathogens, including Staphylococcus aureus, without affecting bacterial growth. Here, the biofilm inhibiting ability of 156 µM ABC-1 was tested in various biofilm-forming strains of S. aureus. It was demonstrated that ABC-1 inhibits biofilm formation by these strains at micromolar concentrations regardless of the strains' dependence on Polysaccharide Intercellular Adhesin (PIA), cell wall-associated protein dependent or cell wall- associated extracellular DNA (eDNA). Of note, ABC-1 treatment primarily inhibited Protein A (SpA) expression in all strains tested. spa gene disruption showed decreased biofilm formation; however, the mutants still produced more biofilm than ABC-1 treated strains, implying that ABC-1 affects not only SpA but also other factors. Indeed, ABC-1 also attenuated the accumulation of PIA and eDNA on cell surface. Our results suggest that ABC-1 has pleotropic effects on several biofilm components and thus inhibits biofilm formation by S. aureus.

Stereochemical Course of Deprotonation-Acylation of N-Boc- and N-Carbamoyl-2-cyano-6-methylpiperidines.

The stereochemical course of electrophilic substitution of α-nitrile metallocarbanions generated by deprotonation from N-Boc- and N-carbamoyl-2-cyano-6-methylpiperidines was investigated. Deprotonation in the presence of an electrophile taking advantage of the high acidity of α-nitrile protons allowed examination of the effects of a chelating group on the nitrogen atom, a countercation, and the reactivity of an electrophile on the steric course. Analyses of reactions using aroyl chlorides and methyl iodide revealed the following: (1) the substitution reactions basically proceed with retention of configuration, (2) the extent of an inversion product increases with decreasing chelating ability of the N-substituent and with increasing leaving ability (ionic character) of a countercation (Li, Na, K) of the anionic species, and (3) the use of a more reactive electrophile results in an increase of the retention product.

Formation of 2-Cyano-2-siloxyvinylallenes via Cyanide-Induced Brook Rearrangement in γ-Bromo-α,ß,γ,δ-unsaturated Acylsilanes.

Reactions of γ-bromo-α,ß,γ,δ-unsaturated acylsilanes with KCN under phase-transfer catalyst conditions using n-Bu4NBr afforded 2-cyano-2-siloxyvinylallenes via a tandem process that involves a nucleophilic attack of a cyanide ion and a Brook rearrangement induced conjugate vinylic 1,4-elimination. Use of a chiral cyanide ion source, derived from KCN and quaternary ammonium bromide derived from cinchona alkaloids, provided nonracemic allene derivatives. Based on this result and the reaction using a chiral hydride ion source, we propose a reaction pathway in which a Brook rearrangement mediated vinylic conjugate 1,4-elimination occurs in a syn alignment between the C-Br bond and C-Si bond in the silicate intermediate.

Transnitrosation of non-mutagenic N-nitrosoproline forms mutagenic N-nitroso-N-methylurea.

N-Nitroso-N-methylurea (NMU) is a potent carcinogen and suspected as a cause of human cancer. In this study, mutagenic NMU was detected by HPLC after the transnitrosation of non-mutagenic N-nitrosoproline (NP) to N-methylurea in the presence of thiourea (TU) under acidic conditions. The structure of NMU was confirmed by comparing (1)H NMR and IR spectra with that of authentic NMU after fractionation by column chromatography. Furthermore, a fraction containing NMU formed by transnitrosation was mutagenic in Salmonella typhimurium TA1535. NMU was formed in the reaction of NP and N-methylurea in the presence of 1,1,3,3-tetramethylthiourea (TTU) or 1,3-dimethylthiourea in place of TU as an accelerator. The reaction rate constants (k) for NMU formation were correlated with their nucleophilicity of sulfur atom in thioureas. The N-methylurea concentration did not affect the NMU formation, whereas the rate of NMU formation correlated linearly with concentrations of NP, TTU and oxonium ion. The observed kinetics suggests a mechanism by which the nitroso group was transferred directly from the protonated NP to the thiourea then to N-methylurea to form NMU. The rate-determining step was the formation of the complex with the protonated NP and thiourea.

Enantioselective synthesis of α-silylamines by Meerwein-Ponndorf-Verley-type reduction of α-silylimines by a chiral lithium amide.

Meerwein-Ponndorf-Verley-type reduction of N-tosylsilylimines with chiral lithium amide 2 affords α-silylamines in high enantioselectivity. Since the enantioselectivity observed was inconsistent with our previously proposed chairlike six-membered transition structure, we performed density functional theory (DFT) calculations on transition states leading to (S)- and (R)-7a and (S)- and (R)-7e using an N-phenylsulfonyl derivatives 12 and 13 as model systems. Results of the calculations showed that the structures are considerably deformed from the chairlike form with steric repulsions between the 1'-methylene group and the imine-carbon substituents playing an important role in the control of the enantioselectivity.

Antisense morpholino targeting just upstream from a poly(A) tail junction of maternal mRNA removes the tail and inhibits translation.

Gene downregulation by antisense morpholino oligonucleotides (MOs) is achieved by either hybridization around the translation initiation codon or by targeting the splice donor site. In the present study, an antisense MO method is introduced that uses a 25-mer MO against a region at least 40-nt upstream from a poly(A) tail junction in the 3'-untranslated region (UTR) of maternal mRNA. The MO removed the poly(A) tail and blocked zebrafish cdk9 (zcdk9) mRNA translation, showing functional mimicry between miRNA and MO. A PCR-based assay revealed MO-mediated specific poly(A) tail removal of zebrafish mRNAs, including those for cyclin B1, cyclin B2 and tbp. The MO activity targeting cyclins A and B mRNAs was validated in unfertilized starfish oocytes and eggs. The MO removed the elongated poly(A) tail from maternal matured mRNA. This antisense method introduces a new application for the targeted downregulation of maternal mRNAs in animal oocytes, eggs and early embryos.

Enantiodivergent deprotonation/acylation of α-amino nitriles.

Back to 'base'ics: The title reaction of enantioenriched α-ureidonitriles was found to proceed in a highly enantiodivergent manner despite the intermediacy of stereolabile α-nitrile metallocarbanions. Enantiodivergence is dependent upon the base used. For the less basic hexamethyldisilazides (HMDS), deprotonation in which a metal (M) cation is precomplexed with an electrophile is proposed. LDA=lithium diisopropylamide.

Tophaceous pseudogout of the temporomandibular joint extending into the cranium: a case report with literature review.

Pseudogout is a disease characterized by calcium pyrophosphate crystal deposition. Involvement of the temporomandibular joint (TMJ) is rare. We herein report a case of tophaceous pseudogout of the TMJ with cranial extension. An 83-year-old woman was referred to our institution for treatment of right TMJ pain. The patient's medical and family histories were unremarkable. Magnetic resonance imaging showed a mass of about 35 mm in diameter compressing the bottom of the right temporal lobe of the brain. Based on a clinical diagnosis of a right TMJ tumour, biopsy was performed under general anaesthesia. The histopathological diagnosis was pseudogout. Considering the risk of surgically induced brain damage, the patient's advanced age and her relatively good quality of life, the treatment plan simply involved the observation of the lesion. Fourteen months after biopsy, the patient's activities of daily living remained unchanged and she had no TMJ pain.

One-pot approach to 2,3-disubstituted-2,3-dihydro-4-quinolones from 2-alkynylbenzamides.

Concise and efficient syntheses of various trans-2,3-disubstituted-2,3-dihydro-4-quinolones have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides, nucleophilic addition of alcohols to the isocyanate intermediates, intermolecular [2+2]-cycloaddition with carbon-carbon triple bonds and aldehydes, and intramolecular aminocyclization of nitrogen of carbamates to the α,ß-unsaturated ketones.

Regio- and stereoselective multisubstituted enol ester synthesis.

Regio- and stereoselective cohalogenation of alkynes with NXS (X = Br, I) was achieved, and the stereoselectivity of the resulting alkenes was dependent on the substituent on the alkyne. Cohalogenation and successive cross-coupling gave multisubstituted enol esters in a one-pot process.

A novel hydrazide type organocatalyst for enantioselective Diels-Alder reactions.

The development of a new class of hydrazide type organocatalyst, (4R,5R)-1,3-bis(isopropylamino)-4,5-dihenylimidazolidin-2-one 2a, for enantioselective Diels-Alder reactions between cyclopentadiene and α,ß-unsaturated aldehydes are presented. The new organocatalyst 2a promoted the reaction, affording Diels-Alder adducts in good yields with good levels of enantioselectivity.

Formal total syntheses of (+)-prelaureatin and (+)-laurallene by diastereoselective brook rearrangement-mediated [3 + 4] annulation.

The formal syntheses of (+)-prelaureatin (1) and (+)-laurallene (2), halogenated eight-membered-ring ethers, are described. The key step of our strategy relies on diastereoselective construction of a trans-alpha,alpha'-disubstituted oxocene structure through a Brook rearrangement-mediated [3 + 4] annulation with acryloylsilane 9 and 6-oxa-2-cycloheptenone derivative 22'.

Platinum-catalyzed, one-pot tandem synthesis of indoles and isoquinolines via sequential rearrangement of amides and aminocyclization.

By using platinum(II) chloride as a Lewis acid catalyst, concise and efficient syntheses of indole carbamates, 1,2-dihydroisoquinoline carbamates, macrocyclic indole carbamates, indole ureas, and indole phosphoranes have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenzamides and 2-alkynylbenzylamides, nucleophilic addition of alcohols and amines to the isocyanate intermediates, and intramolecular aminocyclization of the thus-formed carbamates and ureas to 2-alkynyl functions. A variety of nucleophiles such as alcohols, amines, and stable Wittig reagents could be introduced to the highly electrophilic carbon of the isocyanate intermediates derived from amides. We observed enhancement of the reaction rates when the reactions were run under microwave irradiation.

Crystal structures of the apo and holo form of rat catechol-O-methyltransferase.

Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is a monomeric enzyme that catalyzes the transfer of a methyl group from S-adenosyl-l-methionine (AdoMet) to the phenolic oxygen of substituted catechols. Although the inhibitor recognition pattern and AdoMet site have already been studied crystallographically, structural information on the catalytic cycle of COMT has not yet been obtained. In this study, comparison of the co-factor and inhibitor-bound structures revealed that the Apo form of COMT shows a conformational change and there was no cleft corresponding to the AdoMet-binding site; the overall structure was partially open form and the substrate recognition site was not clearly defined. The Holo form of COMT was similar to the quaternary structure except for the beta6-beta7 and alpha2-alpha3 ligand recognition loops. These conformational changes provide a deeper insight into the structural events occurring in reactions catalyzed by AdoMet.

Crystal structures of rat catechol-O-methyltransferase complexed with coumarine-based inhibitor.

In human, catechol-O-methyltransferase (COMT: E.C. 2.1.1.6) is responsible for metabolism of catechol neurotransmitter and xenobiotics. The main clinical interest in COMT results from the possibility of using COMT inhibitors as adjuncts in the therapy of Parkinson's disease (PD) with l-DOPA. COMT is therefore a target for inhibitor development aiming at PD treatment and has been submitted to extensive structure-based drug design. Recently reported inhibitors have nitrocatechol structure that may inhibit oxidative phosphorylation and uncouple mitochondrial energy production. This work reports the first crystallographic study of Rat COMT complexed with non-nitrocatechol inhibitor. Analysis of the structural differences among the previously reported inhibitor complexes, coumarine-based inhibitor (4-phenyl-7, 8-dihydroxycoumarine: 4PCM) bound structure provides the explanation for inhibitor binding and can be used for future inhibitor design.

Stereoselective S(E)2' protonation of alpha-hydroxyallylsilanes mediated by a Brook rearrangement.

Brooked up! Treatment of (R,Z)-3-(tert-butyldimethylsilyl)-1-cyano-3-hydroxyprop-1-enyl carbamate with a catalytic amount of a base afforded (S,E)-3-(tert-butyldimethylsilyloxy)-1-cyanoallyl diisopropylcarbamate, showing that S(E)2'-type reaction of allylsilicates proceeds in an anti fashion. The overall process is equivalent to trapping of an enantioenriched C-chiral carbanion at the alpha-position of nitrile group in up to 77 % ee (see scheme).

[2,3]-Wittig rearrangement of enantiomerically enriched 3-substituted 1-propenyloxy-1-phenyl-2-propen-1-yl carbanions: effect of heteroatoms and conjugating groups on planarization of an alpha-oxy-benzylcarbanion through a double bond.

Don't get trapped: The effect of conjugating electron-withdrawing groups and alpha-anion-stabilizing heteroatom substituents on configurational stability of chiral carbanions through a double bond was examined on the basis of extent of chirality transfer in intramolecular trapping in [2,3]-Wittig rearrangement of chiral 3-substituted 1-propenyloxy-1-phenyl-2-propen-1-yl carbanions (see scheme).The effect of conjugating electron-withdrawing groups and alpha-anion-stabilizing heteroatom substituents on configurational stability of chiral carbanions through a double bond was examined on the basis of extent of chirality transfer in intramolecular trapping in [2,3]-Wittig rearrangement of chiral 3-substituted 1-propenyloxy-1-phenyl-2-propen-1-yl carbanions.

CD28 stimulation triggers NF-kappaB activation through the CARMA1-PKCtheta-Grb2/Gads axis.

CD28 stimulation contributes to activation of the IL-2 promoter by up-regulating the activity of several transcription factors, including nuclear factor kappaB (NF-kappaB)/Rel family members. However, the signal-transducing cascades linking the CD28 molecule and activation of NF-kappaB remain unclear. Protein kinase C (PKC) , CARMA1 and Bcl10 have recently been reported to integrate TCR-mediated NF-kappaB activation. However, since the data in these studies were drawn from experiments in which T cells were usually stimulated with both TCR and CD28, the relative contributions of TCR- and CD28-mediated signals to initiation of the NF-kappaB pathway remain elusive. To examine the role of these molecules in NF-kappaB activation through CD28-mediated stimulation, Bcl10 was over-expressed in Jurkat cells and their NF-kappaB activation by CD28- or TCR-cross-linking was evaluated. We found that CD28 stimulation alone can induce NF-kappaB activation in Bcl10-over-expressing Jurkat cells, whereas TCR stimulation alone has only little effect. In addition, we found that Bcl10-induced NF-kappaB activation through CD28-mediated stimulation could be blocked by the dominant-negative form of PKC or CARMA1. Furthermore, genetic studies revealed that Grb2/Gads binding, but not phosphatidylinositol 3-kinase binding, is important in CD28-mediated NF-kappaB activation. These findings indicate that the PKC-CARMA1-Bcl10 signaling pathway participates in the CD28 co-stimulatory signal independently of the TCR-signaling pathway, which leads us to propose that the activation of the NF-kappaB-signaling pathway via PKC-CARMA1-Bcl10 may be markedly dependent on CD28 stimulation rather than TCR stimulation.