Stereoselective synthesis of cyclopentanones by reductive cleavage of 6-oxonorbornane-2-carboxylates and its application to the synthesis of 1α,25-dihydroxyvitamin D3 CD ring

Kazuo Nagasawa, Naoto Matsuda, Yasuo Noguchi, Masahiro Yamanashi, Yoshiro Zako, Isao Shimizu

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A novel chiral synthesis of the CD-ring 2 of 1α,25-dihydroxyvitamin D3 (1a) is described. The optically active D-ring keto ester 3c was prepared by reductive cleavage of 6-oxonorbornane-2-carboxylate 4c with lithium naphthalenide. 1,2-Transposition of enone 15, which was obtained by Robinson annulation of 14, was accomplished via thermolysis of the allylic carbonate 29 at 100°C to give enone 16. Reduction of ketone 16 with NaBH4-CeCl3 followed by hydrogenation with RhCl-(PPh3)3 catalyst gave trans-indanol 32, which was transformed to intermediate 2.

Original languageEnglish
Pages (from-to)1483-1490
Number of pages8
JournalJournal of Organic Chemistry
Issue number6
Publication statusPublished - 1993


ASJC Scopus subject areas

  • Organic Chemistry

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