(Chemical Equation Presented) The right way round: Peribysin E, a naturally occurring adhesion inhibitor, has been synthesized and, as a result, its absolute configuration reassigned. The natural and nonnatural enantiomers can be reached starting from (R)- or (S)-carvone, respectively. A key step is the ring contraction of 1 to 2 (see scheme, TBS = tert-butyldimethylsilyl, TES = triethylsilyl).
[Show abstract][Hide abstract] ABSTRACT: The synthesis of lairdinol A, a component of the host-selective phytotoxin depsilairdin, was achieved in 12 steps (18% overall yield) without the use of protecting groups starting with the Diels-Alder reaction of (R)-carvone with 3-trimethylsilyloxy-1,3-pentadiene. The key step established the trans ring fusion by preferential epoxidation of a trans-fused enone in an equilibrating mixture of the cis-fused and trans-fused diastereomers (i.e., equivalent to a dynamic kinetic resolution of these isomers). The synthesis confirms the absolute configurations of lairdinol A and its enantiomer, cyperusol C.
The Journal of Organic Chemistry 03/2008; 73(3):1071-6. DOI:10.1021/jo7024465 · 4.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A convergent, stereocontrolled route to either antipode of the cell adhesion inhibitor, peribysin E, has been achieved from carvone. Highlights of the synthesis include a Diels-Alder reaction to generate a cis-decalin framework, followed by semipinacol-type ring contraction to secure the stereochemistry of the C7 quaternary center. Potential mechanistic pathways for the critical ring contraction were studied through deuterium incorporation studies. In addition, an optimized olefin isomerization/Saegusa oxidation protocol is described for the conversion of [4+2] cycloadducts of 2-(trialkylsilyloxy)-1,3-dienes to 1,6(2H,7H)-naphthalenediones, having stereochemical arrangements not accessible via conventional Robinson annulation protocols. Finally, the ability to independently prepare either enantiomer of peribysin E from the corresponding antipode of carvone led to a reassignment of the absolute configuration of peribysin E.
Journal of the American Chemical Society 10/2008; 130(41):13765-70. DOI:10.1021/ja8048207 · 12.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an overview of the structural diversity of terpenes from marine-derived fungi, highlighting individual examples of chemical structures and placing them in a context of other terpenes of fungal origin. Wherever possible, information regarding the biological activity is presented.
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