Isomerization-Free Allylic Alkylations of Terminal π-Allyl Palladium Complexes
作者:Katja Krämer、Uli Kazmaier
DOI:10.1021/jo061362d
日期:2006.11.1
Chelated amino acid ester enolates are excellent nucleophiles for allylicalkylations. With these enolates, even terminal π-allyl palladium complexes react without significant isomerization. This allows a transfer of the cis-olefin geometry from the substrate into the product. Chiral substrates also show a reasonably good 1,5-induction.
Synthesis of a Vitamin D<sub>3</sub> Hydrindan Ring−Side-Chain Building Block, Involving Tandem Conjugate Addition and Alkylation Reactions
作者:Paweł Grzywacz、Stanisław Marczak、Jerzy Wicha
DOI:10.1021/jo9705834
日期:1997.8.1
Vitamin D-3 hydrindan ring-side-chain building block 4 (racemic) has been synthesized from ketene acetal 12 (derived from 6-methylheptanoic acid), 2-methylcyclopent-2-en-1-one (13), allyl methyl carbonate, and dimethyl methylphosphonate. The Mukaiyama-Michael conjugate addition of 12 and 13 yielded the adduct 11 (lk) accompanied by ca. 10% of its diastereomer. Allylation of 11 with allyl methyl carbonate in the presence of palladium catalyst afforded 10. The latter was transformed into enol lactone 26, which on treatment with 2 equiv of lithium dimethyl methylphosphonate and then 1 equiv of acetic acid provided 4.