Acyclic Stereocontrol Induced by Allylic Alkoxy Groups. Synthetic Applications of Stereoselective Dihydroxylation in Natural Product Synthesis

Abstract

Jin K. Cha received a B.S. degree in chemistry from Seoul National University in 1975. In 1981, he received his D.Phil. degree from University of Oxford, England under the direction of Professor Jack E. Baldwin. The first two years of graduate study were spent at Massachusetts Institute of Technology. After a two-year period of postdoctoral training under Professor Yoshito Kishi at Harvard University, he joined the faculty at Vanderbilt University in 1983. In Fall 1991 he moved to the University of Alabama where he is currently Associate Professor of Chemistry. His research interests include the development and applications of new methods and strategies for natural product synthesis.No-Soo Kim was bom in Seoul, Korea, in 1957. He obtained a B.S. degree in industrial chemistry from Hanyang University, and a M.S. degree in organic chemistry from Korea Advanced Institute of Science. In 1992, he received his Ph.D. in organic chemistry under the direction of Professor James D. White at Oregon State University. His Ph.D. dissertation involved synthetic studies toward trichothecene. After a postdoctoral study at the University of Alabama with Professor J. K. Cha, he joined Youngdong Institute of Technology as an Assistant Professor in Spring 1994. His research interests include the synthesis of biologically active compounds.be exploited to exert a unique stereodirecting effect on adjacent prochiral sp2 sites. In addition, the ready availability of optically pure allylic alcohols by enantioselective reduction of the corresponding ketones lends itself to practical asymmetric synthesis.2'3

Substrate Binding in the Asymmetric Dihydroxylation Reaction − Investigation of the Stereoselectivity in the Dihydroxylation ofCs-Symmetric Divinylcarbinol Derivatives

“…[17] Thus, the expected (1R,2R,3R)-isomer of diol 2e was formed by (Re),-anti-selective dihydroxylation of 1e using AD-mix β. The diol (1R,2R,3R)-2e was stereospecifically converted into the epoxide (1R,2R,3R)-3e [26] and subsequently deprotected to the epoxy alcohol (1R,2R,3R)-3a (Scheme 1).…”

“…The AD reactions of divinylcarbinol derivatives 1, with changes in the size of the alkoxy substituent and variation in the type (DHQD or DHQ) and class (CLB, PHAL, AQN or PYR) of ligands (for structures and abbreviations see Figure 1), give rise to stereochemical information. This can be understood by a combination of Corey's mechanistic proposal and known models [17] for the diastereoselective dihydroxylation of allylic ether derivatives.…”

Total Synthesis of Sphingofungin E and 4,5-Di-<i>epi</i>-sphingofungin E

“…After conversion of aldehyde into alkene, the stereoselective introduction of a diol group via dihydroxylation [52][53][54] of 7 would result in both vinyl intermediates 8 and 9. Such antipodal diastereoselectivity has already been demonstrated in dihydroxylations of substrates having an allylic and/or homoallylic functionality.…”

“…The OsO 4 /NMO dihydroxylation usually results in diastereoselectivity under steric or stereoelectronic control. [52][53][54] The reaction of 7a with catalytic amounts of OsO 4 in the presence of NMO proceeded with the complete facial selectivity to produce diol 11 with 89% yield as a single diastereomer. 64) Donohoe conditions [OsO 4 and tetramethylethylenediamine (TMEDA)] [55][56][57][58][59][60][61][62] were tested with the expectation of antipodal facial selectivity via a hydrogen-bonding mediated process.…”

Simple strategy for synthesis of optically active allylic alcohols and amines by using enantioselective organocatalysis

“…The possible transformations of these important compounds are numerous and proceed often with excellent stereoinduction (1)(2)(3). Consequently, optically active allylic alcohols and amines have appeared innumerable times as key intermediates in asymmetric total syntheses, showing the need for efficient and benign methods of their formation.…”