Reactions with Three- and Four-Membered Ring Systems

Reactions with Three- and Four-Membered Ring Systems 

3-Diphenyl-l-azirine (29) and benzyne yield the 1 1 adduct 31 (50%) and 1 2 adduct 32 (14%).34 The formation of these indoles can be explained by assuming 1,2-cycloaddition of benzyne, reorganization of the strained intermediate 30, and some N-phenylation of 31 by further reaction with benzyne. 

Tabushi, H. Yamada, Z. Yoshida, and H. Kuroda, Tetrahedron Lett., 1093 (1974) L. Lombardo and D. Wege, ibid., 3981. 

Styrene oxide and benzyne are reported to give the 1 1 adducts 35 and 36 (9% and 6% yield, respectively), both derived from the same intermediate 34.36 However, propene oxide is apparently unreactive to benzyne, since its use is advocated to react with the hydrogen chloride which is released when benzyne is generated by decomposition of o-carboxybenzenediazonium chloride (Section II,B).37 37a-b 

Although benzyne is formed by decomposition of 4-phenyl-1,2,3-benzo-triazine (12) above 500°C,18 2-phenylbenzazete (37) has been isolated on a cold finger by flash vacuum pyrolysis of 12 at 420-450°C.38 A by-product of this reaction is 10-phenylacridine (38), which may result from addition of 

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IV. Reactions with Three- and Four-Membered Ring Systems.192... 

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