First Total Synthesis of Piperenol B and Configuration Revision of the Enantiomers Piperenol B and Uvarirufol A

Abstract

We report herein the first total synthesis of piperenol B, a polyoxygenated cyclohexene derivative with reported pharmacological activity isolated from Piper cubeb. The chiral building block for this synthetic approach is derived from microbial cis‐ipso,ortho‐dihydroxylation of sodium benzoate, which was optimized to the multi‐ten‐gram scale by reaction medium engineering. Final‐stage deprotection of an acetonide was investigated in detail, leading to an efficient eight‐step protocol for the synthesis of piperenol B with a total yield of 10 %. Most importantly, the previously assigned absolute configuration of piperenol B was revised and unequivocally established by 2D NMR analysis and the Mosher's ester method.

Polyoxygenated Cyclohexenes and Other Constituents of Cleistochlamys kirkii Leaves

“…They possess antimicrobial, cytotoxic, , anti-inflammatory, and mosquito-larvae growth inhibitory activities. Due to their bioactivity, heptenolides and polyoxygenated cyclohexene derivatives, also including those previously isolated from C. kirkii , have attracted the attention of synthetic chemists. ,− On the basis of its expected richness in such bioactive secondary metabolites possibly useful in the development of novel antimalarial and anticancer agents, and as part of our ongoing search of new antimalarial and anticancer agents as well as our work on the phytochemical characterization of East African medicinal plants, C. kirkii has been reinvestigated. The constituents isolated from its leaves were evaluated for activity against Plasmodium falciparum (3D7, Dd2), human embryonic kidney cells (HEK-293), and human triple-negative breast cancer cells (MDA-MB-231) and luciferase mRNA translational inhibition.…”

New Polyketides from the Marine-Derived Fungus Letendraea Sp. 5XNZ4-2

“…The absolute configuration of 3 was determined by a modified version of Mosher's esterification method [12,13]. Compound 3 was acylated with R-(−)-and S-(+)-α-methoxy-α (trifluoromethyl) phenylacetyl chloride (α-MTPA-Cl).…”

The Synthesis of Certain Phomentrioloxin A Analogues and Their Evaluation as Herbicidal Agents

“…It follows that employed in our synthesis of the “parent” system 1 . Thus, the cis -1,2-dihydrocatechol 32 , which is readily obtained in enantiomerically pure form through the whole-cell biotransformation of iodobenzene, , was converted into the corresponding acetonide under previously defined conditions and thus affording the known and rather unstable compound 33 . Regio- and diastereo-selective cis -dihydroxylation of the nonhalogenated double bond within diene 33 proceeded readily under the UpJohn conditions to give diol 34 (62% from 32 ) that was subject to 2-fold O -methylation using methyl iodide and thus providing the bis-ether 35 in 47% yield.…”