para-Substituted benzylidenetriarylarsoranes with para-substituted benzaldehydes give olefins when the benzylidene para-substituent is strongly electron attractive otherwise epoxides are formed. Methylenetriphenyl-arsorane with αβ-unsaturated ketones gives cyclopropanes and benzylidenetriphenylarsorane with Schiff's bases gives aziridines. Reactions of arsoranes with dimethyl acetylenedicarboxylate, phenylsulphine, and phenylsulphene are also described.