Alkenes Beckmann rearrangement-addition

The Beckmann rearrangement is used in a similar way to produce the lactam 32, an intermediate in the synthesis of swainsonine 33. Stereoselective addition of dichloroketene to the enol ether 30 gave one isomer ( 95 5) of cyclobutanone 31. Beckmann rearrangement with a sulfonated hydroxylamine and dechlorination gave the lactam 32 in 34% yield over five steps7 from a precursor of 30. Note that the m-alkene 30 gives the trans cyclobutanone selectively. 

In addition to carbon-carbon bond forming reactions of derived anions, hydrazones and oximes are important derivatives of carbonyl groups for the Beckmann rearrangement (of oximes to amides, equation 55)203.204 jmd the Shapiro reaction (tosylhydrazones to alkenes, equation 56). ° Of historical... 

Generation of Electrophilic Cations. Complexation of Et2AlCl to ketones and aldehydes activates the carbonyl group toward addition of a nucleophilic alkyl- or allylstannane or allylsilane. Et2AlCl has been used to initiate Beckmann rearrangements of oxime mesylates. The ring-expanded cation can be trapped intermolecularly by enol ethers and cyanide and in-tramolecularly by alkenes (eq 5). ... 

EtAlCb catalyzes the Friedel-Crafts acylation of alkenes with acid chlorides, the formal [3 + 2] cycloaddition of alkenes with cyclopropane-1,1-dicarboxylates (eq 21), the Friedel-Crafts alkylation of anilines and indoles with ct-aminoacrylate esters, and the formation of allyl sulfoxides from sulfinyl chlorides and alkenes. EtAlCU induces the Beckmann rearrangement of oxime sulfonates. The cationic intermediates can be trapped with enol silyl ethers (eq 22). EtAlC is the preferred catalyst for addition of the cation derived from an a-chloro sulfide to an alkene to give a cation which undergoes a Friedel-Crafts alkylation (eq 23). ... 

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