Nonracemic alpha-allenyl carbinols from asymmetric propargylation with the 10-trimethylsilyl-9-borabicyclo[3.3.2]decanes.
[reaction: see text] The asymmetric propargylboration of aldehydes at -78 degrees C in <3 h with 1 provides silylated alpha-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 alpha-hydroxy acid quantitatively with water.
Hernandez
Eliud
E
University of Puerto Rico, Department of Chemistry, Rio Piedras, Puerto Rico 00931-3346.
Soderquist
John A
JA
D000447:Aldehydes / Q000737:chemistry*; D000473:Alkanes / Q000737:chemistry*; D002384:Catalysis; D000432:Methanol / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
D000447:Aldehydes; D000473:Alkanes; D014297:Trimethylsilyl Compounds; C012867:decane; D000432:Methanol