Nonracemic 3 degrees-carbamines from the asymmetric allylboration of N-trimethylsilyl ketimines with B-allyl-10-phenyl-9-borabicyclo[3.3.2]decanes.
The simple and efficient asymmetric synthesis of 3 degrees -carbamines 7 from N-TMS enamines (3) and either enantiomeric form of beta-allyl-10-(phenyl)-9-borabicyclo[3.3.2]decane (1) is reported. The high reactivity (<1 h, -78 degrees C) and enantioselectivity (60-98% ee) of these substrates can be attributed to the fact that the complexation of 3 with 1 facilitates its isomerization to the corresponding syn-N-TMS ketimine complex from which allylation can occur. In addition to providing the homoallylic amines 7 with predictable stereochemistry, the procedure also permits the efficient recovery of the chiral boron moiety (50-65%) as air-stable crystalline pseudoephedrine complexes 8, which are directly converted back to 1 with allylmagnesium bromide in ether (98%).
Canales
Eda
E
Department of Chemistry, University of Puerto Rico, Rio Piedras, Puerto Rico.
Hernandez
Eliud
E
Soderquist
John A
JA
D000498:Allyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D000588:Amines / Q000138:chemical synthesis* / Q000737:chemistry; D001896:Boron Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008968:Molecular Conformation; D017646:Organosilicon Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D000498:Allyl Compounds; D000588:Amines; D001896:Boron Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D007097:Imines; D017646:Organosilicon Compounds