The Synthesis of Some Cyclopropane and Spirane Hydrocarbons¹

Spiroannulated Cyclopropanes

“…The required gem-(dihalomethyl) cycloalkanes are usually prepared by halogenation of the precursor diols (equation 1). The cyclization is most efficiently accomplished in the Zn-alcohol-water system 10,11 . For example, spiro[2.5]octane 7 was prepared in 91% yield using this procedure 11 .…”

“…The cyclization is most efficiently accomplished in the Zn-alcohol-water system 10,11 . For example, spiro[2.5]octane 7 was prepared in 91% yield using this procedure 11 . This method is useful even for a one-step preparation of bis-spirocyclopropyl compounds as exemplified in equation 2 12 .…”

“…However, the method might be very useful for the synthesis of bisspirocyclopropyl compounds. For example, dispiroketone 13 was prepared according to equation 11 and was used as a starting material in the synthesis of [5]rotane 29 …”

“…The syntheses of rotanes accomplished in the 1970s demonstrated interesting solutions to this problem. An improved method of preparation of this compound is based on cyclopropanation of 7-methylenedispiro[2.2.1]heptane (11) 19,53,54 . This olefin was originally prepared by reductive cyclization of dibromide 10 (equation 5) 20 .…”

Short Synthesis of a Taxane-AB-Fragment with a Spiro-Cyclopropyl Group

“…Several procedures for the hydrogenolytic ring opening of cyclopropanes are described. [13][14][15][16] Catalysts for ring opening are nickel on kieselgur 13 and palladium on activated carbon. 14 The hydrogenolysis of the cyclopropane ring to a geminal dimethylgroup can often be achieved in glacial acetic acid employing platinum(IV)-oxide as a catalyst.…”