Oa-1 Α,β-unsaturated Α’-halomethylsulfones: Prepackaged Ramberg-bäcklund Reagents for Tandem Synthetic Processes
نویسندگان
چکیده
“Prepackaged” Ramberg–Bäcklund reagents may be defined as compounds having sulfonyl and α-halogen groups which, following an appropriate first step, require only base to give by Ramberg–Bäcklund (“RB”) reaction olefinic end products with an increase in total number of carbon atoms. The synthesis and reactions of several previously unknown α,β-unsaturated chloromethyl sulfones is presented, extending our earlier work on chloromethanesulfonyl-1,3-propadiene (Scheme 1). We describe our studies with chloromethanesulfonylethene and dichloromethanesulfonylethene, which serve as useful allene or 1,1-dichloroallene synthons, respectively, in tandem Diels-Alder-RB reactions (Scheme 2), as well as (E,Z)-1,2-bis(chloromethanesulfonyl)ethene, employed in the first example of a tandem ene-RB sequence. Efforts to use newly prepared 1-chloromethanesulfonyl-1-haloethenes (CH2=CXSO2CH2Cl) in tandem RB processes will also be described.
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