Hept-2-enose reaction

Interaction of 4,5 6,7-di-0-cyclohexylidene-2,3-dideoxy-l-C-phe-nyl-L-arafeino-hept-2-enose (65) with phenylmethylenetriphenylphos-phorane was accompanied9 6 by the formation of triphenylphosphine, instead of the expected triphenylphosphine oxide, thus indicating the abnormal character of this reaction. This result may be interpreted as involving possible addition of the phosphonium ylide to the alkenic bond, with subsequent stabilization of the intermediate betaine 82 through elimination of triphenylphosphine, and closure of the three-membered ring2(f) with formation of the cyclopropane derivative 83, as shown in equation 5. 

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