Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst.

The cobalt/chromium-catalyzed three-component coupling of aryl iodides, allenes, and aldehydes has been developed to afford multi-substituted homoallylic alcohols in a diastereoselective manner. Control experiments for understanding the reaction mechanism reveal that the cobalt catalyst is involved in the oxidative addition and carbometalation steps in the reaction, whereas the chromium salt generates highly nucleophilic allylchromium intermediates from allylcobalt species, without the loss of stereochemical information, to allow the addition to aldehydes.

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones.

Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,ß-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products.

Practical Stannylation of Allyl Acetates Catalyzed by Nickel with Bu3 SnOMe.

A practical and scalable nickel-catalyzed allylic stannylation of allyl acetates with Bu3 SnOMe is described. A variety of acyclic and cyclic allyl acetates, even with base-sensitive moieties, undergoes the stannylation by using NiBr2 /4,4'-di-tert-butylbipyridine (dtbpy)/Mn catalyst system to afford highly functionalized allyl stannanes with excellent regioselectivity and yields. Furthermore, the scope of protocol is also extended by the reaction of propargyl acetates, giving rise to propargyl or allenyl stannanes. Additionally, a unique diastereoselectivity using the nickel catalyst different from the palladium was demonstrated for the stannylation of cyclic allyl acetates. In the reaction, inexpensive and stable nickel complexes, abundant reductant (Mn), and atom-economical stannyl source were used.

A Sn atom-economical approach toward arylstannanes: Ni-catalysed stannylation of aryl halides using Bu3SnOMe.

Stannylation of carbon-halogen bonds is one of the most promising and straightforward approaches for the preparation of organostannane compounds. Although a wide variety of methods are now available, all protocols require the use of highly nucleophilic organometals or wasteful stannyl sources like distannanes. Here, we report a new nickel-catalysed stannylation of aryl and alkenyl-halides using Bu3SnOMe as a stannyl source to afford aryl and vinyl-stannanes, respectively. This method enables the stannylation of not only bromides, but also chlorides and triflates to furnish functionalized aryl- and alkenyl-stannanes without the release of wasteful and toxic stannyl byproducts.

Cobalt-catalyzed formal [4+2] cycloaddition of α,α'-dichloro-ortho-xylenes with alkynes.

A formal [4+2] cycloaddition of α,α'-dichloro-ortho-xylenes with various alkynes has been developed using a low-valent cobalt catalyst. The transformation has a wide substrate scope and high functional-group tolerance and led to 1,4-dihydronaphthalenes. The formed cycloadducts were easily aromatized with MnO2 under air. A mechanistic investigation suggests that the transformation proceeds through a benzyl cobaltation of alkyne, not the classical Diels-Alder reaction of ortho-quinodimethanes. This methodology provides a straightforward and streamlined access to linearly expanded π-conjugated aromatics.

Clinical features and prognosis of conjunctival melanoma in Japanese patients.

PURPOSE: To evaluate the clinical features and prognosis of conjunctival melanoma in Japanese patients. STUDY DESIGN: Retrospective observational case series. METHODS: Twenty patients (8 men and 12 women) diagnosed with conjunctival melanoma at a singlehospital between 2003 and 2017 were analyzed. Data on clinical presentation, sex, age, the affected eye, tumor location, tumor origin, tumor stage according to the American Joint Committee on Cancer staging system (eighth edition), treatment, outcomes, local recurrence, metastasis, and survival were extracted from the patients' medical records and reviewed. RESULTS: The mean age at diagnosis was 64.2 ± 14.8 years. Tumor locations at the first examination included the bulbar conjunctiva (n = 19), plica (n = 13), and fornix (n = 12). The tumor stage was T1 in 5 cases (25%), T2 in 12 cases (60%), T3 in 3 cases (15%), and T4 in none. The mean follow-up duration was 91.7 ± 46.0 months. The local recurrence rates at 1, 5, and 10 years were 5.0%, 18.8%, and 31.5%, respectively, whilst the metastasis rates were 5.0%, 25.6%, and 32.4%, respectively. Four of the 6 patients who experienced metastasis died; duration from metastasis to death was 17.5 months (range, 7-25). The 5-year survival rate for conjunctival melanoma was 78.8%. Tumor thickness was significantly associated with survival duration on univariate Cox regression analyses. CONCLUSION: The mortality rate for conjunctival melanoma in the Japanese population was lower and higher than that reported in the Chinese and United States populations, respectively. Tumor thickness was a prognostic factor for survival in patients with conjunctival melanoma.

A Randomized Crossover Study in Single-Sided Deafness Comparing a Cartilage Conduction CROS System and an Air-Conduction CROS System.

OBJECTIVE: To investigate if cartilage conduction (CC) rerouting devices are noninferior to air-conduction (AC) rerouting devices for single-sided deafness (SSD) patients by measuring objective and subjective performance using speech-in-noise tests that resemble a realistic hearing environment, sound localization tests, and standardized questionnaires. STUDY DESIGN: Prospective, single-subject randomized, crossover study. SETTING: Anechoic room inside a university. PATIENTS: Nine adults between 21 and 58 years of age with severe or profound unilateral sensorineural hearing loss. INTERVENTIONS: Patients' baseline hearing was assessed; they then used both the cartilage conduction contralateral routing of signals device (CC-CROS) and an air-conduction CROS hearing aid (AC-CROS). Patients wore each device for 2 weeks in a randomly assigned order. MAIN OUTCOME MEASURES: Three main outcome measures were 1) speech-in-noise tests, measuring speech reception thresholds; 2) proportion of correct sound localization responses; and 3) scores on the questionnaires, "Abbreviated Profile of Hearing Aid Benefit" (APHAB) and "Speech, Spatial, and Qualities of Hearing Scale" with 12 questions (SSQ-12). RESULTS: Speech reception threshold improved significantly when noise was ambient, and speech was presented from the front or the poor-ear side with both CC-CROS and AC-CROS. When speech was delivered from the better-ear side, AC-CROS significantly improved performance, whereas CC-CROS had no significant effect. Both devices mainly worsened sound localization, whereas the APHAB and SSQ-12 scores showed benefits. CONCLUSION: CC-CROS has noninferior hearing-in-noise performance except when the speech was presented to the better ear under ambient noise. Subjective measures showed that the patients realized the effectiveness of both devices.

Copper-catalyzed three-component borylstannylation of alkynes.

Regio- and stereoselective installation of boryl and stannyl moieties into a carbon-carbon triple bond of various alkynes has been achieved based on a three-component coupling reaction by using a diboron and a tin alkoxide with the aid of a copper(II) acetate-tricyclohexylphosphine complex, giving diverse vic-borylstannylalkenes in a straightforward manner. Carbon-tin and carbon-boron bonds of the resulting borylstannylation product are successively transformed into carbon-carbon bonds by a Migita-Kosugi-Stille and a Suzuki-Miyaura coupling, leading to the formation of (Z)-tamoxifen with anti-breast cancer activity.

Copper-Catalyzed B(dan)-Installing Carboboration of Alkenes.

Carboboration of alkenes was found to occur readily with an unsymmetrical diboron [(pin)B-B(dan)] and alkyl halides under copper catalysis, leading to the direct formation of protected alkylboron compounds via synchronous C-C and C-B bond-forming processes. The B(dan) moiety was solely installed into the organic frameworks with the regioselective attachment to a terminal carbon of alkenes employed.

The drastic effect of cobalt and chromium catalysts in the borylation of arylzinc reagents.

A new synthetic approach to arylboronic esters from arylzinc reagents with boryl electrophiles MeOB(OR)2 has been developed. Furthermore, this protocol could be applied to the cyclization/borylation of alkynylaryl iodides to afford cyclized vinylboronic esters.

Direct mono-insertion of isocyanides into terminal alkynes catalyzed by rare-earth silylamides.

Rare-earth silylamide complexes, Ln[N(SiMe3)2]3 (Ln = Y, La, Sm, Yb), effectively catalyzed the coupling reaction of isocyanides with both aliphatic and aromatic terminal alkynes under mild conditions.

A masked diboron in Cu-catalysed borylation reaction: highly regioselective formal hydroboration of alkynes for synthesis of branched alkenylborons.

The use of a masked diboron as a boron source in the presence of a Cu-N-heterocyclic carbene (NHC) catalyst enables alkyl-, aryl-, heteroatom- and silyl-substituted terminal alkynes to undergo α-selective formal hydroboration to give diverse branched alkenylboron compounds exclusively. Synthetic potential of this α-selective hydroboration has been demonstrated by total synthesis of pharmaceutically significant bexarotene and LG100268.

Silver-catalyzed highly regioselective formal hydroboration of alkynes.

A silver(I)-N-heterocyclic carbene complex has proven to be a potent catalyst for formal hydroboration of alkynes, providing a variety of borylalkenes in regio- and stereoselective manners. Under the silver catalysis, allenes also undergo regioselective hydroboration to give borylalkenes.

N-heterocyclic carbene-catalyzed double acylation of enones with benzils.

Thiazolium carbene-catalyzed reaction of aromatic 1,2-diketones with enones in aprotic solvents gave double acylation products in good yields, whereas hydroacylation products formed by Stetter reaction were not detected at all. These results suggested the generation of aroyloxyenamine species from the 1,2-diketones instead of hydroxyenamines (Breslow intermediates).

Copper-catalyzed distannylation of alkynes.

A copper(I)-phosphine complex has been found to facilely promote the distannylation of alkynes with the aid of a base, where a catalytically generated Cu-Sn species serves as a key intermediate. The broad versatility of the copper catalysis has been demonstrated by the facile distannylation of unfunctionalized aliphatic alkynes, being hardly achievable with the conventional palladium catalysts.

Copper-catalyzed three-component carboboration of alkynes and alkenes.

Carboboration of alkynes was found to take place efficiently by a three-component coupling reaction with diboron and carbon electrophiles under copper catalysis to afford diverse multisubstituted borylalkenes in a stereoselective manner. The carboboration was also applicable to alkenes, leading to the formation of multisubstituted borylalkanes via regioselective carbon-boron and carbon-carbon bond-forming processes.