In a previous paper') we described the generation of o-lithiomethylphenyl isocyanide, which was a versatile reagent for syntheses of indole derivatives. Herein, we wish to report an elaboration of the lithiomethylphenyl isocyanide to lead to heterocycles such as 4,5-dihydro-3,1-benzoxazepine ~~ and 4H-5,6-dihydro-3,1-benzoxazocine (5) derivatives. o-(b-Hydroxyalkyl)phenyl isocyanides K), which were prepared by the reactions of olithiomethylphenyl isocyanide with aldehydes or ketones, were heated with a catalytic amount of Cu20 in benzene to produce 4,5-dihydro-3,1-benzoxazepine derivatives (( in excellent yields. R* 1 2 3 The intramolecular cyclization reaction is based upon the copper catalyzed insertion reaction of isonitriles into the oxygen-hydrogen bond of alcohols which was found by us. 2) A sample procedure is illustrated as follows. To o-lithiomethylphenyl isocyanide, which was generated in situ at -78ยฐC by treating 176 mg (1.5 mmol) of c-tolyl isocyanide with lithium diisopropylamide (LDA) (3.0 mnol) in 4 ml of diglyme according to the reported procedure, 1) was dropwise added 174 mg (3.0 mmol) of propionaldehyde. The red color characteristic of the lithiomethylphenyl isocyanide disappeared immediately. The reaction mixture was quenched at -78ยฐC with aq NH4Cl, extracted with ether, dried over Na2S04 and evaporated. The residue was distilled 2087