Highly Enantioselective Proton-Initiated Polycyclization of Polyenes
摘要:
This report describes the synthesis of a range of chiral polycyclic molecules (tricyclic to pentacyclic) from achiral polyene precursors by enantio-selective proton-initiated polycyclization promoted by the 11 complex of o,o'-dichloro-BINOL and SbCl5. Excellent yields (ca. 90% per ring formed) and enantioselectivety (20:1 to 50:1) were obtained. The process is practical as well as efficient, because the chiral ligand is both readily prepared from R,R- or S,S-BINOL and easily recovered from the reaction mixture by extraction.
The compounds of the formula I
are precursors for organoleptic and antimicrobial compounds. The latter are generated in the presence of skin bacteria, enzymes or acidic or alkaline conditions. One precursor molecule can provide one or more different compounds.
Regiochemical diversity in allylic alkylations via molybdenum catalysts
作者:Barry M. Trost、Mark Lautens
DOI:10.1016/s0040-4020(01)87666-3
日期:1987.1
the more substituted end of an allyl system regardless of the positional identity of the initial leaving group exists. With β-ketoesters, substrates which possess a secondary and a primary carbon in the allyl unit lead to preferential attack at the secondary carbon. However, substrates that possess a tertiary and a primary carbon at the termini lead to attack at the primary carbon. Anions derived from
The compounds of the formula I
are precursors for organoleptic and antimicrobial compounds. The latter are generated in the presence of skin bacteria, enzymes or acidic or alkaline conditions. One precursor molecule can provide one or more different compounds.
式 I 的化合物
是感官和抗菌化合物的前体。后者在皮肤细菌、酶或酸性或碱性条件下生成。一个前体分子可以提供一种或多种不同的化合物。
Carbonates for the delivery of aldehydes and/or ketones