Enantioselective Intramolecular [2 + 2 + 2] Cycloaddition of Enediynes for the Synthesis of Chiral Cyclohexa-1,3-dienes
作者:Takanori Shibata、Hiroshi Kurokawa、Kazumasa Kanda
DOI:10.1021/jo070762d
日期:2007.8.1
The enantioselective intramolecular [2 + 2 + 2] cycloaddition of various enediynes, where two acetylenic moieties are connected by a trans-olefinic moiety, gave chiral tricyclic cyclohexa-1,3-dienes using Rh-H8-BINAP catalyst. In the case of carbon-atom-tethered enediynes, enantioselectivity was generally good-to-high regardless of the substituents on their alkyne termini. In contrast, with heteroatom-tethered
Have a good SIP: P‐stereogenic secondaryiminophosphorane (SIP) ligands with a sulfonyl group attached to nitrogen have been prepared. In the presence of rhodium, the tautomeric equilibrium is shifted from the favored PHtautomer towards the PIII tautomer, thereby allowing coordination of the SIP ligand through the P and O atoms. The resulting Rh complexes are effective in the [2+2+2] cycloaddition