[Structure: see text] A new Brønsted acid-assisted chiral Brønsted (chiral BBA) acid catalyst (1) was developed by substituting a hydroxy group of optically active 1,1'-bi(2-naphthol) with a stronger Brønsted acidic group such as a bis(trifluoromethanesulfonyl)methyl group. The enantioselective Mannich-type reaction of ketene silyl acetals with aldimines catalyzed by (R)-1 in the presence of stoichiometric achiral proton sources gave (S)-beta-amino esters in high yield with moderate to good enantiomeric excesses.

Chiral aluminum Lewis acid catalyst composed of Me(3)Al and 3,3'-bis(trimethylsilyl)-BINOL in a 2:1 ratio was found to promote novel catalytic asymmetric ring expansion of cyclohexanone with α-substituted α-diazoacetates to give seven-membered rings with an all-carbon quaternary center. Application of this strategy to 4-substituted cyclohexanones opened up a novel way for the catalytic desymmetrizing asymmetric construction of cycloheptanones bearing remote α,δ-chiral centers.

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A nickel complex/Lewis acid combination effectively catalyzed the direct silyl-Heck reaction of chlorosilanes, which are key raw materials in the organosilicon industry, to give synthetically important alkenylsilane products. Trichlorosilanes, dichlorosilanes, and monochlorosilanes underwent the silyl-Heck reaction to afford the corresponding alkenylsilanes in high yields. In the reactions of dichlorosilanes, a single substitution occurred to give monoalkenylsilanes in a highly selective manner.

Asymmetric redox C-C bond formation between alpha-alkyl-alpha-diazocarbonyl compounds and aldehydes was developed as a practical and general method for the construction of alpha-alkyl-beta-keto imides having a chiral nonracemic tertiary stereogenic center.

General Information. Infrared (IR) spectra were recorded on a Shimadzu IRPrestige-21 spectrometer. 1 H NMR spectra were measured on a JEOL JNM-FX400 (400 MHz) spectrometer. Data were reported as follows: chemical shifts in ppm from tetramethylsilane as an internal standard, integration, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, dd = double-doublet, dt = double triplet, m = multiplet, br = broad, and app = apparent), coupling constants (Hz), and assignment. 13 C NMR spectra were measured on a JEOL JNM-FX400 (100 MHz) spectrometer with complete proton decoupling. Chemical shifts were reported in ppm from the residual solvent as an internal standard. High-resolution mass spectra (HRMS) were performed on Brucker microTOF. Optical rotations were measured on a JASCO DIP-1000 digital polarimeter. For thin layer chromatography (TLC) analysis throughout this work, Merck precoated TLC plates (silica gel 60 GF 254 , 0.25 mm) were used. The products were purified by flash column chromatography on silica gel 60 (Merck, 230-400 mesh).In experiments requiring dry solvent, dichloromethane and toluene ware purchased from Kanto Chemical Co. Inc. as "Dehydrated" and further purified by passing through neutral alumina under nitrogen atmosphere. Aldehydes were purchased or prepared according to the procedures 1 and used after distillation or column chromatography on silica gel. Aryldiazoacetates were synthesized according to the procedure 2 and purified by column chromatography on silica gel.

The enantioselective desymmetrizing conjugate hydrosilylation of prochiral differently γ,γ-disubstituted cyclohexadienone derivatives 2 to furnish the corresponding cyclohexenones 4 with a remote chiral all-carbon quaternary center at the γ position is described. Chiral rhodium-bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with high enantiomeric ratios.

Insertion of one methylene unit into the C-C bond of cyclohexanones is a potentially useful, straightforward method for the construction of seven-membered carbocycles. An especially appealing but largely unexplored method in this arena is the nucleophilic addition of diazoalkanes to the Lewis acid-activated cyclohexanones and subsequent ring expansion accompanied by the extrusion of nitrogen (direct Tiffeneau-Demjanov-type ring expansion). Our primary finding is the unprecedented insertion of alpha-alkyldiazoacetates to cyclohexanone and its heteroanalogues, generating seven-membered rings with one all-carbon quaternary center. On the basis of this finding, highly diastereoselective ring expansion of substituted cyclohexanones was developed, furnishing seven-membered rings with 1,4-quaternary-tertiary, 1,4-quaternary-quaternary, or 1,3,5-quaternary-tertiary-tertiary stereogenic centers in a single operation starting from readily available materials. The stereochemical outcome of the product can be easily predicted from the conformation of starting cyclohexanones. Enantioenriched products could be also accessed by the use of (-)-phenylmenthyl alpha-alkyldiazoacetates.