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Abstract The reactions of 3‐phenyl‐1‐azabicyclo1.1.0butane ( 4 ) with dimethyl dicyanofumarate (( E )‐ 8 ) and dimethyl dicyanomaleate (( Z )‐ 8 ) lead to the same mixture of cis ‐ and trans ‐4‐phenyl‐1‐azabicyclo2.1.1hexane 2,3‐dicarboxylates ( cis ‐ 11 and trans ‐ 11 , resp.; Scheme 3 ). This result of a formal cycloaddition to the central CN bond of 4 is interpreted by a stepwise reaction mechanism via a relatively stable zwitterionic intermediate 10 , which could be intercepted by morpholine to give a 1 : 1 : 1 adduct 12 , which undergoes a spontaneous elimination of HCN to yield the fumarate 13 ( Scheme 4 ).
Mlostoń et al. (Wed,) studied this question.