ChemInform Abstract: Wagner-Meerwein Rearrangement of 4-Hydroxymethylpentacyclo(4.3.0.02,5. 03,8.04,7)nonane to Pentacyclo(5.3.0.02,6.03,9.04,8)decane in Formic Acid

The cationic rearrangement of 1-bromo-4-[hydroxybis(4-methoxyphenyl)methyl]pentacyclo[4.3.0.02,5.03,8.04,7]nonane-9-spiro-2′-[1,3]dioxolane (1) in formic acid gave 4-bromo-1-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane in 27% yield along with 5-bromo-9-formyloxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane in 55% yield. The reaction of 1 with p-toluenesulfonic acid or hydrochloric acid in methanol also afforded 4-bromo-1-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,6.03,9.04,8]decane-5-spiro-2′-[1,3]dioxolane together with 5-bromo-9-methoxy-10,10-bis(4-methoxyphenyl)pentacyclo[5.3.0.02,5.03,9.04,8]decane-6-spiro-2′-[1,3]dioxolane. With respect to migration of the C4–C5 bond in the pentacyclo[4.3.0.02,5.03,8.04,7]nonane (homocubane) skeleton to pentacyclo[5.3.0.02,6.03,9.04,8]decane (D2h-bishmocubane), a rearrangement into the bishomocubane system in driven by a concomitant release of strain; also...