enantioselective nucleophilic 1,2‐additions (ee values up to 97 %) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto‐assemble when mixing, in a 1:1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully
Efficient general asymmetric syntheses of 3-substituted 1(3H)-isobenzofuranones in very high enantiomeric excess
作者:P.Veeraraghavan Ramachandran、Guang-Ming Chen、Herbert C. Brown
DOI:10.1016/0040-4039(96)00260-2
日期:1996.3
intermolecular asymmetric reduction of methyl o-(1-oxoalkyl)benzoates with B-chlorodiisopinocampheylborane provides, after workup, 3-alkylphthalides in ≥97% ee. Unfortunately, this procedure is not as efficient for the preparation of 3-arylphthalides. However, an intramolecular reduction of B-(o-benzoylbenzoyloxy)diisopinocampheylborane, readily prepared by the treatment of o-benzoyl benzoic acid with diisopinocampheylborane
and low E factor. This success can be ascribed to the higher reactivity of allylic alcohols as compared with the allyl ester products in soft Ru/hard Brønstead acid combined catalysis, which can function under slightly acidic conditions unlike the traditional Pd-catalyzed system. Detailed analysis of the stereochemical outcome of the reaction using an enantiomerically enriched D-labeled substrate
The first asymmetric hydrogenation of 3‐ylidenephthalides has been developed using the IrI complex of a spiro[4,4]‐1,6‐nonadiene‐based phosphine‐oxazoline ligand (SpinPHOX) as the catalyst, affording a wide variety of chiral 3‐substituted phthalides in excellent enantiomeric excesses (up to 98 % ee). The utility of the protocol has been demonstrated in the asymmetricsynthesis of chiral drugs NBP and
A direct efficient diastereoselective synthesis of enantiopure 3-substituted-isobenzofuranones
作者:Rafael Pedrosa、Sonia Sayalero、Martina Vicente
DOI:10.1016/j.tet.2006.08.058
日期:2006.10
single diastereoisomer. That compound reacted with different organometallics leading to 3 in excellent de. Hydrolysis of carbinols, followed by oxidation of the intermediates allowed for the synthesis of enantiopure phthalides.