The catalytic, enantioselective [2 + 2] cycloaddition reaction of 1-methoxyallenylsilanes with a-imino ester has been achieved by means of the [Cu(MeCN)(4)]BF4/(R)-Tol-BINAP catalyst to afford 3-methylene-azetidine 2-carboxylates in good yields and with excellent enantiomeric excesses. The acid-catalyzed ring opening of the azetidines afforded chiral acylsilanes quantitatively.
Preparation of 3-Alkyl-Substituted 1-Alkoxyallenes – Synthetic and Mechanistic Aspects
作者:Arndt Hausherr、Hans-Ulrich Reissig
DOI:10.1055/s-0037-1609688
日期:2018.7
diacetone-fructose-derived auxiliary. Two diastereomeric 3-alkyl-substituted 1-alkoxyallenes are formed during the isomerization, the ratio being strongly dependent on the reaction conditions. The mechanisticaspects of these observations are discussed on the basis of deuteration experiments and the configurational stability of the ambident propargyl-allenyl carbanion involved. Two routes to 3-alkyl-substituted