Trienediolates of hexadienoic acids in synthesis. Addition to unsaturated ketones. A convergent approach to the synthesis of retinoic acids
作者:Maria J. Aurell、Luisa Ceita、Ramon Mestres、Margarita Parra、Amparo Tortajada
DOI:10.1016/0040-4020(95)00114-n
日期:1995.3
The regioselectivity of the addition of the lithium trienediolates generated from hexa-2,4dienoic acids 1 and 2 or the dihydropyran-2ones 4 and 5 to unsaturated ketones 6 is studied. Equilibration conditions favour reaction of the trienediolates through their ω carbon, and the ketones according to 1,2- and 1,4-additions. β-Ionone 6a and the aryl-butenone 6b lead to the 1,2-ω-adducts 8, which undergo
Titanocene-Catalyzed Reduction of Lactones to Lactols
作者:Xavier Verdaguer、Marcus C. Hansen、Scott C. Berk、Stephen L. Buchwald
DOI:10.1021/jo971560s
日期:1997.11.1
A convenient method for the conversion of lactones to lactols is described. The hydrosilylation to lactols is carried out via air-stable titanocene difluoride or a titanocene diphenoxide precatalyst using inexpensive polymethylhydrosiloxane (PMHS) as the stoichiometric reductant. These procedures have been demonstrated with a variety of substrates and proceed in good to excellent yield.
Diastereoselective oxygen to carbon rearrangements of anomerically linked enol ethers and the total synthesis of (+)-(S,S )-(cis-6-methyltetrahydropyran-2-yl)acetic acid, a component of civet
作者:Darren J. Dixon、Steven V. Ley、Edward W. Tate
DOI:10.1039/b001243m
日期:——
range of enol ethers, linked via their oxygen atom to the anomeric centre of a pyran ring system, was shown to undergo oxygen to carbon rearrangement upon treatment with a Lewisacid to give the corresponding 2-carbon substituted products. At low temperature, trimethylsilyl trifluoromethanesulfonate catalysed rearrangements of anomerically linked 6-substituted tetrahydropyranyl enol ethers gave selectively