910787-07-4Relevant academic research and scientific papers
Nonracemic 3°-carbamines from the asymmetric allylboration of N-trimethylsilyl ketimines with B-allyl-10-phenyl-9-borabicyclo[3.3.2]decanes
Canales, Eda,Hernandez, Eliud,Soderquist, John A.
, p. 8712 - 8713 (2007/10/03)
The simple and efficient asymmetric synthesis of 3°-carbamines 7 from N-TMS enamines (3) and either enantiomeric form of β-allyl-10-(phenyl)-9-borabicyclo[3.3.2]decane (1) is reported. The high reactivity (1 h, -78 °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%). Copyright
B-ally-10-Ph-9-borabicyclo[3.3.2]decanes: Strategically designed for the asymmetric allylboration of ketones
Canales, Eda,Prasad, K. Ganeshwar,Soderquist, John A.
, p. 11572 - 11573 (2007/10/03)
The simple and efficient syntheses of B-allyl-10-(phenyl)-9-borabicyclo[3.3.2]decane (1) in both enantiomeric forms are reported. The remarkable enantioselectivity (81-99% ee) of these reagents in the allylboration process at -78 °C is only modestly diminished when the process is conducted at 0 °C, a phenomenon attributable to its rigid bicyclic structure. In addition to providing the homoallylic alcohols 6 efficiently (70-92%), the procedure also permits the efficient recovery of the chiral boron moiety (67-82%) as an air-stable crystalline N-methylpseudoephedrine complex 4 for the direct regeneration of 1 with allylmagnesium bromide in ether (98%). The reagent gives predictable stereochemistry, providing a strategically designed "chiral pocket" which is particularly receptive to leading methyl groups (e.g., methyl ethyl ketone, 87% ee). Copyright
