95465-56-8Relevant academic research and scientific papers
Chiral Aluminum Catalyst System for the Enantioselective Addition of Vinylaluminum Reagents to Aldehydes: Metal Controlled Reversal of Enantioselectivity
Adate, Priyanka A.,Matsunaga, Takuya,Shin, Hirata,Harada, Toshiro
, p. 3688 - 3693 (2016)
A chiral aluminum catalyst system has been developed for the enantioselective vinylation of aldehydes. β,β-Disubstituted (E)-vinylaluminum reagents, generated regio- and stereoselectively by the carboalumination of terminal alkynes with trimethylalumunim (Me3Al), were used straightforwardly without transmetalation to vinyltitanium reagents in the subsequent enantioselective addition to aldehydes with a DPP-H8-BINOL-derived chiral aluminum catalyst at low catalyst loading (5 mol%). The reaction afforded the corresponding enantiomerically enriched secondary allylic alcohols with a reversal of the selectivity observed in closely related reactions catalyzed by a chiral titanium complex derived from the same ligand. (Figure presented.).
Oxidative rearrangement of 2-alkoxy-3,4-dihydro-2H-pyrans: stereocontrolled synthesis of 4,5-cis-disubstituted tetrahydrofuranones including whisky and cognac lactones and crobarbatic acid
Armstrong, Alan,Ashraff, Cassim,Chung, Hunsuk,Murtagh, Lorraine
experimental part, p. 4490 - 4504 (2009/10/09)
Oxidation of 2-alkoxy-3,4-dihydro-2H-pyrans 3 with dimethyldioxirane or MTO/urea-H2O2 followed by Jones oxidation leads to rearrangement and stereocontrolled formation of 4,5-cis-disubstituted tetrahydrofuranones. The method is applied to the synthesis of the whisky lactone 9, cognac lactone 10 and crobarbatic acid 17.
Platinum-catalyzed addition of dimethylsilylene to β-methyl α-β-unsaturated ketones: γ-silylation forming 1-Oxa-2-silacyclohex-5-enes
Okamoto, Kazuhiro,Hayashi, Tamio
, p. 5067 - 5069 (2008/03/27)
The reaction of β-methyl α,β-unsaturated ketones with pentamethyldisilane in the presence of a platinum catalyst brought about silylation on the β-methyl group giving high yields of oxasilacyclohexenes.
Stereochemical Aspects in the Insertion by Alkylidenemethylene Carbenoids into the α-C-H Bond of Alkoxides
Oku, Akira,Harada, Toshiro,Hattori, Kazuhiro,Nozaki, Yohko,Yamaura, Yasunari
, p. 3089 - 3098 (2007/10/02)
Primary alkoxides (R1CH2OM; M=K or Li) when treated with haloalkenes (R3R4C=CXY; X=Cl or Br, Y=H or Cl) in the presence of n-BuLi in THF at 0 deg C gave allylic alcohols (R1CH(OH)CH=CR3R4) through the insertion reaction of the corresponding alkylidenemethylene carbenoid () into the α-C-H bond of alkoxides.Secondary alkoxides (R1R2CHOM), under similar reaction conditions, gave butyl adducts (R1R2C(OH)C4H9) in addition to the insertion products.In particular, the C-H insertion of menthyl oxide proceeded without stereospecificity to give a mixture of the axial and equatorial insertion products.These results provided evidence for the hydride abstraction-recombination mechanism in the carbenoid insertion reaction.The regioselective, nonstereospecific insertion reaction was also observed when alkoxides were treated with separately prepared ((2,3-benzo-2-cyclohexylidene)chloromethyl)lithium at temperatures from -95 to -40 deg C.The absence of H-D scrambling in crossover experiments under these reaction conditions clearly showed that the hydride abstraction-recombination mechanism proceeded within a solvent cage.An inversion of configuration on the carbenoid carbon in the hydride abstraction step was proposed on the basis of the E/Z stereoselectivity in the insertion products.
