Stereocontrolled synthesis of spiro[n.2]alkenes by ring contraction of fused-cyclobutanols.
An unusual ring-contraction rearrangement to give spirocyclopropanes from fused cyclobutanols (see scheme) has been developed. It is found that the strain energy of the substrates derived from an additional fused ring and the stereoelectronic effect of the migrating sigma bond are important factors. It is noteworthy that the rearrangement proceeds in a stereospecific manner. Moreover, the method provides a spiro(cyclopropane-indane) framework from tricyclo[6.3.0.02,5]undecane, which corresponds to illudane and the protoilludane skeleton.
Takasu
Kiyosei
K
Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan. kay-t@pharm.kyoto-u.ac.jp
Nagamoto
Yuuki
Y
Takemoto
Yoshiji
Y
D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D003503:Cyclobutanes / Q000737:chemistry*; D003521:Cyclopropanes / Q000737:chemistry*; D015394:Molecular Structure; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D000475:Alkenes; D003503:Cyclobutanes; D003521:Cyclopropanes; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D013141:Spiro Compounds; C538814:cyclobutanol; C506221:protoilludane