73307-77-4Relevant academic research and scientific papers
The total synthesis of (-)-aplysin via a lithiation-borylation- propenylation sequence
Fletcher, Catherine J.,Blair, Daniel J.,Wheelhouse, Katherine M.P.,Aggarwal, Varinder K.
, p. 7598 - 7604 (2012)
A concise, highly enantioselective synthesis of sesquiterpene natural products (-)-debromoaplysin and (-)-aplysin has been completed. The key steps included lithiation-borylation of a secondary benzylic carbamate to give a tertiary boronic ester followed by propenylation which installed the quaternary stereocenter with complete enantioselectivity. Subsequent RCM followed by deprotection and in situ cyclization led to debromoaplysin with good diastereoselectivity from which the target compound was prepared in just eight overall steps.
Total Synthesis of (-)-Aplysin and (-)-Debromoaplysin
Ronald, Robert C.,Gewali, Mohan B.,Ronald, Bruce P.
, p. 2224 - 2229 (2007/10/02)
The total synthesis of optically active (-)-aplysin (1) and (-)-debromoaplysin (2) employing novel (isopinocampheyloxy)methyl ethers for phenolic hydroxyl protection and diastereomeric resolution is described.A key transformation is the unusual cyclization of the diastereomeric chlorohydrins 12 and 13 in methanolic base to form the enantiomeric tricyclic alcohols (-)-16 and (+)-16 with cleavage of the acetal-linked (isopinocampheyloxy)methyl resolving/protecting group.This transformation was followed by substitution of the tertiary hydroxyl via the derived chloride with a methyl group by Grignard coupling with methylmagnesium bromide.The methyl insertion occurred with retention of configuration and resulted in formation of the natural aplysin system from 12 in just three steps.The conversion of the methylated tricyclic ether 20 to (-)-debromoaplysin (2) was accomplished in two steps by double bond isomerization and selective reduction.Bromination of (-)-2 afforded (-)-aplysin (1).
