Helical primary structures of four-membered rings: (M)-trispiro[3.0.0.3.2.2]tridecane

The synthesis of (M)-trispiro[3.0.0.3.2.2]tridecane [], the first hydrocarbon with a helical primary structure of four-membered rings, is described. Key step is the kinetic resolution of a cyclobutanone through reduction with bakersʹ yeast. As compared to its analogue of three-membered rings, (M)-trispiro[2.0.0.2.1.1]nonane [], the specific rotation of is cut in three. According to molecular mechanics calculations this could be due to a potential to adopt different conformations, not given in , and to the fact, that describes a distinctly shorter section of a helix than .