54565-04-7Relevant articles and documents
Selective Catalytic Transesterification, Transthiolesterification, and Protection of Carbonyl Compounds over Natural Kaolinitic Clay
Ponde, Datta E.,Deshpande, Vishnu H.,Bulbule, Vivek J.,Sudalai, Ammugam,Gajare, Anil S.
, p. 1058 - 1063 (1998)
Transesterification and transthiolesterification of β-keto esters with variety of alcohols and thiols and selective protection of carbonyl functions with various protecting groups catalyzed by natural kaolinitic clay are described. The clay has been found to be an efficient catalyst in transesterifying long chain alcohols, unsaturated alcohols, and phenols to give their corresponding β-keto esters in high yields. For the first time, transthiolesterification of β-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of β-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding β-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward β-keto esters is also described. Sterically hindered carbonyl groups as well as α,β-unsaturated carbonyl groups underwent protection without the deconjugation of the double bond. Chemoselective protection of aldehydes in the presence of ketones has also been achieved over natural kaolinitic clay.
Mg2+-imidazole-catalyzed self-condensation of malonyl thioesters: Getting tuned for biomimetic polyketide synthesis?
Sakai, Naomi,Sorde, Nathalie,Matile, Stefan
, p. 845 - 851 (2007/10/03)
We report that a subtle balance of carbanion reactivity, leaving group activation, and pKa of the catalyst is required for efficient self-condensation of thiomalonates to thioacetoacetates in up to 71% yield under "biomimetic" conditions originally proposed by Kobuke and Yoshida (Tetrahedron Lett. 1978, 19, 367).
