Chemical and nuclear magnetic resonance studies of 3,3‐diphenyltetrahydrofuran derivatives

Pyrolytic cyclization of a‐ and β‐methadol methiodides afforded cis and trans isomers of 2‐ethyl‐3,3‐diphenyl‐5‐methyltetrahydrofuran, respectively. Catalytic hydrogenation of 2‐ethyli‐dene‐3,3‐diphenyl‐5‐methyltetrahydrofuran yielded the cis and trans isomers in a 2:1 ratio. The nmr spectra of these and structurally related compounds have been analyzed in terms of a half‐chair conformation for 2‐ethyl‐5‐methyl, 2‐ethyl, and 5‐methyl derivatives. An envelope conformation has been suggested for the compounds containing a double bond at C‐2.