Studies On The Dehydroxymethylation Ofα-Alkenoyl Ketene Dithioacetals

Since Kelber first synthesized the a-benzoyl ketene dithioacetals in1910, a-oxo ketene dithioacetals chemistry has become an important division in organic chemistry. In recent three decades, quite lots of documents have been published in this area, and some reviews were successively reported to summarize these results. Generally, the reaction types of a-oxo ketene dithioacetals mainly include the conjugate addition-cyclization with nitrogen nucleophilic species, regioselective addition-aromatization with organometallic reagents, acting as odorless dithiol equivalents in thioacetalization and michael additions, nucleophilic reactions of a-carbon, as well as the synthetic applications based on the above reactions.a-alkenoyl ketene dithioacetals are easily prepared and bear much more reaction center. They are usually utilized as the synthetic active intermediates. From the viewpoint of structures, a-alkenoyl ketene dithioacetals have the following characters:(1) could be viewed as the1,5-bielectrophilic five-carbon units.(2) the alkylthio groups are good leaving-groups, facilitated the SNV reaction.(3) bear a variety of functional groups. Recently, our research group developed the [5+1] annulation of a-alkenoyl ketene dithioacetals, various carbo-/hetero-cyclic compounds such as poly-substituted cyclohexene, phenol, pyrrolizidine, pyrimidine, thiopyran ketone etc. were synthesized. It provides a new synthetic method for six-membered carbo-/hetero-cyclic compounds.Based on the research achievements in our research group on a-alkenoyl ketene dithioacetals chemistry, we utilize a-alkenoyl ketenedithioacetals as the1,5-bielectrophilic five-carbon components, their reactions with nucleophiles are studied with the combination of [5+1] annulation and dehydroxymethylation. A new synthetic methodology for the construction of six-membered carbocyclic compounds is developed. And a series of cyclohexenones were synthesized via a general and simple method.