DIMETHYL SULFOXIDE-TRIFLUOROACETIC ANHYDRIDE - NEW REAGENT FOR OXIDATION OF ALCOHOLS TO CARBONYLS
DIMETHYL SULFOXIDE-TRIFLUOROACETIC ANHYDRIDE - NEW REAGENT FOR OXIDATION OF ALCOHOLS TO CARBONYLS
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DOI：
10.1021/jo00868a012
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发表时间：
1976-01-01
影响因子：
3.6
通讯作者：
SWERN, D
中科院分区：
文献类型：
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作者：
OMURA, K;SHARMA, AK;SWERN, D
以二甲基亚砜(Me2SO)和三氟乙酸酐(TFAA)为原料，在-50℃以下的二氯甲烷中原位合成三氟乙酰氧基二甲基三氟乙酸酯，与醇快速反应生成烷氧基二甲基三氟乙酸酯和三氟乙酸乙酯。将三乙胺(TEA)添加到烷氧基硫酸盐中，可根据醇的结构和反应条件，生成不同量且可控的羰基化合物、烷基三氟乙酸酯和烷基甲基硫甲醚。羰基的产率按伯烯丙醇、次烯丙醇和苄基醇的顺序增加。当TEA在室温下而不是低于-50摄氏度时，或当使用更多的溶剂时，从伯醇和仲醇中生成的羰基的产率最高。在最佳反应条件下，伯醇的产率为60%，仲醇的产率为80%-85%，苄基和某些烯丙醇的产率为80%-100%。在适当的条件下，在烯丙基或苄基的存在下，伯羟基和仲羟基的选择性氧化都可以实现。提出了解释产物分布的反应途径。
Trifluoroacetoxydimethylsulfonium trifluoroacetate prepared in situ from dimethyl sulfoxide (Me2SO) and tri-fluoroacetic anhydride (TFAA) below-50 C in methylene chloride reacts rapidly with alcohols togive alkoxydimethylsulfonium trifluoroacetates and trifluoroacetic acid. Addition of triethylamine (TEA) to the alkoxysulfonium salts gives carbonyl compounds, alkyl trifluoroacetates, and alkyl methylthiomethyl ethers in varying and controllable amounts depending on the structure of the alcohols and reaction conditions. Yields of carbonyls in-crease in the order primary< secondary< allylic and benzylic alcohols. Yields of carbonyls from primary and sec-ondary alcohols are highest when TEA is added to the alkoxysulfonium salts at room temperature rather than below-50 C, or when larger amounts of solvent are employed. Under optimum conditions, yields of carbonyls are in the range of 60% from primary alcohols, 80-85% from secondary alcohols, and 80-100% from benzylic and certain allylic alcohols. Under appropriate conditions, selective oxidation of primary and secondary hydroxyl groups can be effected in the presence of allylic or benzylic hydroxyl groups. Reaction pathways to account for product distribution are proposed.