Super-electrophiles vinylation

There have been several studies utilizing the ability of 4,6-dinitrobenzofuroxan (DNBF) to act as a super-electrophile. It has been shown that the initial product of its reaction with phenoxide ions is the O-bonded adduct (29), although this rearranges to give die C-bonded adduct.117 The reaction of DNBF with ethyl vinyl ether yields a dihydrooxazine A -oxidc cycloadduct as a mixture of two diastereoisomers, and in the presence of excess ether a di-adduct (30) is formed.118 Rate constants have been reported for the reaction of DNBF with 3-methoxythiophene in DMSO-water mixtures. The reaction results in a er-adduct which is the product of Se-At substitution in the thiophene, and the results were used to probe the carbon basicity of the thiophene derivative.119... 

The double deprotonation of 2-arylnitroethanes followed by treatment wiA electrophiles led to 2-sub-stituted-2-arylnitroethanes. This fact suggested that the strong base sequentially abstracted a- and then (3-protons of these substrates giving a,(3-dianions (57). The same behavior has been observed with primary nitroalkanes having a vinyl or carbonyl group on the 3-carbon. If there is only one a-nitro CH as in open-chain and cyclic secondary nitroalkanes, bis(lithioxy)enamines (58) and (59) (dianion derivatives of a-nitroalkenes, also called super enamines) are generate and exclusively those with a terminal double bond in the case of 2-nitroalkanes (equations 22 and 23). These dianion derivatives react with aromatic and aliphatic aldehydes as well as ketones to give 1,3-difunctional derivatives. In contrast to the lack of... 

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