Natural kaolinitic clay possessing transition metals such as Fe and Ti in its lattice has been found to catalyze efficiently the chemoselectiveacetalization and thioacetalization of variety of carbonyl compounds with ethane-1,2-diol and ethane-1,2-dithiolrespectively.
Elimination of β-Thioalkoxy Alcohols under Mitsunobu Conditions. A New Synthesis of Conjugated Enynes from Propargylic Dithioacetals
作者:Chih-Wei Chen、Tien-Yau Luh
DOI:10.1021/jo8013885
日期:2008.11.7
Treatment of propargylic dithiolanes 1 with (n)BuLi followed by a carbonyl electrophile yields the corresponding homopropargylic alcohol 3. Upon treatment with 2 equiv of PPh3 and DIAD, elimination of SR and OH moieties from 3 affords the corresponding olefins 4 in moderate to good yield. The reaction can be considered an alternative of McMurry coupling of two different carbonyl equivalents.
Described are furyl and phenyl mercaptals defined according to the generic structure: ##STR1## wherein the dashed line represents a carbon-carbon single bond or no bond; wherein R.sub.1 and R.sub.2 are the same or different and each represents hydrogen, methyl or ethyl; wherein p is 0 or 1; and wherein X represents a phenyl moiety having the structure: ##STR2## or a furyl moiety having the structure: ##STR3## and uses thereof in augmenting or enhancing the aroma or taste of foodstuffs.
Furyl and phenyl mercaptals and use thereof in augmenting or enhancing
申请人:International Flavors & Fragrances Inc.
公开号:US04515968A1
公开(公告)日:1985-05-07
Described are furyl and phenyl mercaptals defined according to the generic structure: ##STR1## wherein the dashed line represents a carbon-carbon single bond or no bond; wherein R.sub.1 and R.sub.2 are the same or different and each represents hydrogen, methyl or ethyl; wherein p is 0 or 1; and wherein X represents a phenyl moiety having the structure: ##STR2## or a furyl moiety having the structure: ##STR3## and uses thereof in augmenting or enhancing the aroma or taste of foodstuffs.
Selective Catalytic Transesterification, Transthiolesterification, and Protection of Carbonyl Compounds over Natural Kaolinitic Clay
作者:Datta E. Ponde、Vishnu H. Deshpande、Vivek J. Bulbule、Arumugam Sudalai、Anil S.Gajare
DOI:10.1021/jo971404l
日期:1998.2.1
Transesterification and transthiolesterification of beta-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 beta-keto esters in high yields. For the first time, transthiolesterification of beta-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of beta-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding beta-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward beta-keto esters is also described. Sterically hindered carbonyl groups as well as alpha,beta-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.