General approach to cycloalkanone synthesis. Intramolecular alkylation of 2-chloro-1-olefins

Synthesis of Substituted Hydrindanes. Part I. Products Arising from the Cyclization of Acetonyl Cyclohexanones and Acetonyl Cyclohexadiones

“…attempt cyclization in concentrated acids, as described by Lansbury (2). We had previously failed to prepare en01 esters or ethers with the terminal double bond.…”

Ab → Abc → Abcd

“…Subsequent hydrogénation and oxidation led to cZZ-equilenin methyl ether (35). In later studies [19] it was found that, for large scale preparation of cZZ-equilenin methyl ether (35), it was more effiicient to [20] also synthesized the urinary steroid 40 and its 3a-epimer, starting from equilenin (23) and dihydroequilenin (41).…”

“…A facile, three-step synthesis of cis-16-equilenone methyl ether, starting with 46, was developed by Lansbury and co-workers [41]. Treatment of the ketone 46 with 2,3-dichloropropene in presence of sodium hydride and Λ/,Ν-dimethylformamide was followed by reduction with lithium aluminum hydride to give 52.…”

Bc → BCD → Abcd

“…Another variation of the above approach utilizing intramolecular cyclization is exemplified by the synthesis of the eis ketone 189, which was achieved by treatment of the alcohol 188 with sulfuric acid at 0°C [121]. As described in Chapter 3 (Scheme 3-6), this method was utilized for the stereospecific synthesis of c/s-16-equilenone methyl ether.…”