Dimethylzinc‐Mediated, Enantioselective Synthesis of Propargylic Amines.

Abstract

Amines Q 0120Dimethylzinc-Mediated, Enantioselective Synthesis of Propargylic Amines. -A previously reported synthesis of propargylic amines is extended to the use of alkynes (III) by simple modification of the reaction conditions. The enantioselective variant of this method is successfully accomplished by use of stoichiometric or substoichiometric amounts of enantiopure amino alcohol AAC as a chiral inducer. -(ZANI, L.; EICHHORN, T.; BOLM*, C.; Chem. Eur. J. 13 (2007) 9, 2587-2600; Inst. Org.

Recent Developments in Asymmetric Alkynylation of Imines

“…By using this ligand, tosyl benzaldimine led to the corresponding product in 96 % ee. An additional improvement of the reaction was observed when the solvent volume was reduced by 50 %, in agreement with the reports by Bolm [66,67]. Under the optimized conditions, a number of representative N-tosyl arylaldimines underwent addition of phenylacetylene with consistently high enantioselectivities (87-100 % ee), regardless of their steric or electronic nature (Scheme 79).…”

“…These authors also have developed a one-pot synthesis of propargylic amines, which made use of various aldehydes 48, o-methoxyaniline (210), alkynes (19) and dimethylzinc (2 M in toluene) as starting materials. The reaction provided the expected propargylic amines 83 with acceptable to good yields for a range of aldehydes and alkynes (Scheme 75) [67]. However, the electron-poor alkyne methyl propiolate (R = CO 2 Me) was not applicable to the reaction.…”