is therefore generated in situ from trichloroacetohydroximoyl chloride (4)['l.
While oxepin reacts directly with ( 1 ) to give (3), reaction of ( 1 ) with 1,3-cyclohexadiene gives cycloadduct ( 5 ) as intermediate. This thermally labile compound rearranges even at room temperature, and more rapidly on heating, to give (2) in quantitative yield. C1, Cl 8 ( I ) f clTcl I NOH C1 I 6 0 C13C-C,
The structures of the products ( ) and ( 3 ) follow from their 'H-and I3C-NMR spectra (see Table ). In the case of (2) the NMR data are comparable with those of the adduct of 1,l -dichloro(nitroso)ethene and cyclopentadiene[" and with those of the diepoxy-I ,3-~yclohexadiene[~I.
The vicinal coupling constant 3Jl,2 in the 'H-NMR spectrum of (2) is compatible only with a cis configuration. The [silica gel; cyclohexane/ether (1 : I)]; the isomers (2) and
(5) are obtained in variable ratio (overall yield: 85 %). ( 5 ) : colorless liquid; IR (CHCI,): v=2980, 1590 cm-'; 'H-NMR (CDCI,): F=2.33--1.17 (4H, m), 3.90 (IH, m), 4.57 (1H, m), 6.45(2H,dofm). ( ): whitesolid,m. p. 64-65"C; IR (CHC13): v=2990, 1595 cm-'; MS: m/e=239 (M'), 204, 136, 95, 77, 67. [6.1.0.02~4.0s~7]nonane (3): 50ml of a solution of ( l ) , prepared as above, is added dropwise with stirring at -20°C to a solution of 2.0g of the oxepin['] in dichloromethane. After 6 h at room temperature, the solvent is evaporated off and the residue is purified by column chromatography (silica gel; CHC1,). Yield of (3), m.p. 135-136"C, 17%. IR (CHC13): v=2990, 1600, 880 cm-I; MS: m/e=253 ( M + ) , 160, 129, 94, 81, 53. 9-Trichloroethenyl-trans-3,6-dioxa-9-azatetracyc~o-