616206-05-4Relevant academic research and scientific papers
An Asymmetric Synthesis of Hamigeran B via a Pd Asymmetric Allylic Alkylation for Enantiodiscrimination
Trost, Barry M.,Pissot-Soldermann, Carole,Chen, Irwin,Schroeder, Gretchen M.
, p. 4480 - 4481 (2007/10/03)
A protocol for the asymmetric allylic alkylation of a five-membered ring ketone derivative that employs the lithium enolate in the presence of lithium alkoxides gave high yields and enantioselectivities. This product serves as a versatile intermediate as demonstrated in a convergent total synthesis of the antiviral agent hamigeran B. The sequence involves two unusual observations. In the intramolecular Heck reaction which establishes the complete ring sytem, the β-H elimination step occurs both endocyclic (as expected) and exocyclic, the latter most surprising since it creates an exocylic tetrasubstituted double bond. In the catalytic hydrogenation, use of Pd/C gives complete selectivity for net delivery of hydrogen to the most hindered face of the substrate, whereas use of Ir black gives complete selectivity for delivery of hydrogen to the least hindered face. Such unusual behavior speaks to the unusual chemical properties associated with hamigeran B which may be relevant to its biological activity. Copyright
Enantiospecific total synthesis of 6-epi-(-)-hamigeran B. Intramolecular Heck reaction in a sterically constrained environment
Mehta, Goverdhan,Shinde, Harish M.
, p. 7049 - 7053 (2007/10/03)
An enantiospecific approach, emanating from the abundantly available chiron R-(+)-limonene, to the biologically potent, novel marine natural products, the hamigerans has been developed in which an intramolecular Heck coupling between aryl triflates and an alkene serves as the pivotal step. Following this strategy, a synthesis of (-)-6-epi-hamigeran B has been accomplished.
