Nonracemic α-Allenyl Carbinols from Asymmetric Propargylation with the 10-Trimethylsilyl-9-borabicyclo[3.3.2]decanes†
journal contributionposted on 24.11.2005, 00:00 by Eliud Hernandez, John A. Soderquist
The asymmetric propargylboration of aldehydes at −78 °C in <3 h with 1 provides silylated α-allenyl carbinols 6 (60−87%) in high ee (94% to >98% ee). The reagents 1 are easily prepared in both enantiomeric forms with a simple Grignard procedure and air-stable borinate complexes 2. The ozonolysis of 6 proceeds smoothly through an acylsilane intermediate to give a TMS ester, which is hydrolyzed to the α-hydroxy acid quantitatively with water.