3-Cyclohexene-1 -carboxamide rearrangement

Although iodine(III) reagents attack double bonds, the rearrangement of the amide group is, at least in some cases, more rapid than electrophilic attack on alkenes. Thus 3-cyclohexene-l-carboxamide rearranges smoothly to the corresponding amine as long as only one equivalent of [1,1-bis(trifluoroacetoxy)iodojbenzene is used. 

Other methods for the preparation of cyclohexanecarboxaldehyde include the catalytic hydrogenation of 3-cyclohexene-1-carboxaldehyde, available from the Diels-Alder reaction of butadiene and acrolein, the reduction of cyclohexanecarbonyl chloride by lithium tri-tcrt-butoxy-aluminum hydride,the reduction of iV,A -dimethylcyclohexane-carboxamide with lithium diethoxyaluminum hydride, and the oxidation of the methane-sulfonate of cyclohexylmethanol with dimethyl sulfoxide. The hydrolysis, with simultaneous decarboxylation and rearrangement, of glycidic esters derived from cyclohexanone gives cyclohexanecarboxaldehyde. 

PIFA easily converts succinic acid derivatives (32) to -alanine derivatives (33). Limited use of PIFA (1 equiv.) allows the rearrangement of 3-cyclohexene-1-carboxamide (34) without oxidation of the double bond, as shown in Scheme 12. Cyclohexanone is obtained by the PIFA oxidation of 1-cyclohex-enecarboxamide (35). Selective oxidation of the primary amide (36) occurs without effect on secondary or tertiary amides in the same molecule. The rearrangement of the cyclopropane derivative (37) accompanies the ring cleavage to give the -alanine derivative (38) after treatment with benzyloxycarbonyl chloride. ... 

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