Subtle but distinctive: The stereostructure of the biologically highly promising antimitoticagentleiodermatolide was uncertain. A short, efficient, and flexible totalsynthesis based on ring‐closing alkyne metathesis as the key step has now solved the puzzle. Subtle differences in the 1H NMR spectra of the structure shown and the conceivable isomer proved invaluable for the assignment.
微妙但与众不同:生物学上很有前途的抗有丝分裂剂leiodermatolide的立体结构尚不确定。以开环炔烃复分解为关键步骤的短而有效且灵活的全合成方法现已解决了这个难题。所示结构和可能的异构体在1 H NMR光谱中的细微差异证明对于该赋值是无价的。
Nonracemic 3°-Carbamines from the Asymmetric Allylboration of <i>N</i>-Trimethylsilyl Ketimines with <i>B</i>-Allyl-10-phenyl-9-borabicyclo[3.3.2]decanes
作者:Eda Canales、Eliud Hernandez、John A. Soderquist
DOI:10.1021/ja062242q
日期:2006.7.1
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
<i>B</i>-Allyl-10-Ph-9-borabicyclo[3.3.2]decanes: Strategically Designed for the Asymmetric Allylboration of Ketones
作者:Eda Canales、K. Ganeshwar Prasad、John A. Soderquist
DOI:10.1021/ja053865r
日期:2005.8.24
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