Synthesis 2019; 51(09): 1995-2000
DOI: 10.1055/s-0037-1610686
paper
© Georg Thieme Verlag Stuttgart · New York

Selectivity Control in Terpene Rearrangements: A Biomimetic Synthesis of the Halimanic Bicyclic Core

Tatiana Sîrbu
a   Laboratory of Natural and Biologically Active Compounds Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova   Email: kulcitki@yahoo.com
,
Vladilena Girbu
a   Laboratory of Natural and Biologically Active Compounds Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova   Email: kulcitki@yahoo.com
,
Petru Harghel
a   Laboratory of Natural and Biologically Active Compounds Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova   Email: kulcitki@yahoo.com
,
Vasile Rusu
b   Laboratory of Ecological Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova
,
Nicon Ungur
a   Laboratory of Natural and Biologically Active Compounds Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova   Email: kulcitki@yahoo.com
,
a   Laboratory of Natural and Biologically Active Compounds Chemistry, Institute of Chemistry, Ministry of Education, Culture and Research, str. Academiei 3, MD 2028, Chişinău, Republic of Moldova   Email: kulcitki@yahoo.com
› Author Affiliations
Financial support from the Supreme Council for Science and Technology Development, Academy of Sciences of Moldova (Project No. 15.817.02.14A) is gratefully acknowledged. V.K. acknowledges the ­Alexander von Humboldt Foundation for a postdoctoral fellowship.
Further Information

Publication History

Received: 18 September 2018

Accepted after revision: 17 December 2018

Publication Date:
19 February 2019 (online)


Abstract

The bicyclic core of the halimanic framework is synthesized in optically active form by an acid-induced rearrangement of a homo­drimanic epoxide. The substrate can follow two different pathways under acidic treatment. Using fluorosulfonic acid as a promoter at low temperature favors ring contraction to a perhydrindanic structure. In contrast, milder acids at higher temperatures bring about predominantly an angular methyl migration and formation of the halimanic bicyclic system. In particular, an acidic pillared clay selectively promoted this transformation.

Supporting Information