The presence of this moiety on docarmycin and ptaquiloside makes them exceptional DNA alkylating agents.
The presence of this moiety on docarmycin and ptaquiloside makes them exceptional DNA alkylating agents. It's not an epoxide, but in cholesterol biosynthesis the dimerization of farnesyl pyrophosphate generates an intermediate with this moiety that spontaneously collapses to give squalene. The divinyl version of this compound can isomerize to cycloheptadiene in a Cope-like reaction. 1,4 dienes exposed to light rearrange to a substituted form of it in the di-pi-methane rearrangement. Charge-shift bonding is used to explain the structure of a molecule containing three of these moieties sharing a bond, called [1.1.1]-propellane. Because its interorbital angles are (*) 104 degrees, this molecule can be considered to have sp5 hybridization. This molecule occurs as an intermediate during the conversion of alpha-halo ketones to carboxylic acids in the Favorskii reaction. Because of its unusual reactivity, AD Walsh described this molecule's MO's as a combination of methylene units. It is generated by treating an alkene with diiodomethylzinc in the Simmons-Smith reaction. Banana-bonds are used to describe its highly deviated bond angles. For 10 points, name this simplest cyclic hydrocarbon. 
The presence of this moiety on docarmycin and ptaquiloside makes them exceptional DNA alkylating agents.
Cyclopropane