Semisynthetic Enzymes in Asymmetric Synthesis: Enantioselective Reduction of Racemic Hydroperoxides Catalyzed by Seleno-Subtilisin
作者:Dietmar Häring、Ellen Schüler、Waldemar Adam、Chantu R. Saha-Möller、Peter Schreier
DOI:10.1021/jo981665a
日期:1999.2.1
The serine protease subtilisin was chemically converted into the peroxidase-active seleno-subtilisin. This semisynthetic enzyme catalyzes the enantioselective reduction of racemic hydroperoxides in the presence of thiophenols to yield optically active hydroperoxides and alcohols on the semipreparative scale. The kinetic parameters and enantioselectivities of seleno-subtilisin-catalyzed reduction of
Tandem Ring-Closing/Cross-Metathesis Approach for the Synthesis of Synargentolide B and Its Stereoisomers
作者:Gowravaram Sabitha、Kontham Shankaraiah、Jhillu S. Yadav
DOI:10.1002/ejoc.201300434
日期:2013.8
stereoisomers have been accomplished from L-(+)- and D-(–)-diethyl tartrates, D-ribose, and D-mannitol as chiral pool starting materials. The key step was a tandem ring-closing/cross-metathesis reaction in which lactone formation and fragment coupling were accomplished in one pot. The spectroscopic data of synthetic product 2c were in agreement with those reported for the natural product. Synargentolide
Bacterial Biotransformation of Isoprene and Related Dienes
作者:Derek R. Boyd、David Clarke、Marcel C. Cleij、John T. G Hamilton、Gary N. Sheldrake
DOI:10.1007/s007060070096
日期:2000.6.15
Pseudomonas putida ML 2 was used in the oxidative biodegradation of the acyclic dienes isoprene, trans -piperylene, cis -piperylene, and 1,3-butadiene. Regioselective dioxygenase-catalyzed dihydroxylation of alkenes yielded vicinal diols in the preferred sequence monosubstituted > cis -disubstituted > gem -disubstituted > trans -disubstituted. The isolated diol metabolites had an excess of the R
细菌 恶臭假单胞菌 在无环二烯烃的氧化降解,使用ML 2异戊二烯, 反式 -piperylene, 顺 -piperylene,和1,3-丁二烯。区域选择性双加氧酶催化的烯烃的二羟基化产生邻位二醇,优选的顺序为单取代> 顺式- 二取代> 宝石- 二取代> 反式- 二取代。分离出的二醇代谢物具有过量的 R 构型(9–97% ee ),并通过加入丙二醇作为抑制剂来控制进一步的二醇氧化。使用ML2菌株的立体选择性是由于酶的不对称烯烃二羟基化和二醇的动力学拆分而产生的。 R 构型的烯丙基仲醇基团的对映选择性氧化产生相应的不饱和酮醇 。回收的残留二醇的 S 构型大大过量(≥93% ee ) 。除了产生不饱和二醇和酮醇的酶二烯氧化步骤之外,还发现了酶烯加氢产生饱和酮醇和二醇的证据。
Optically Active Epoxy Diols by Titanium-Catalyzed Oxidation of Enantiomerically Enriched Hydroperoxy and Hydroxy Homoallylic Alcohols
作者:Waldemar Adam、Marion N. Korb、Chantu R. Saha-Möller
The Ti-catalyzed epoxidation of opticallyactive (S,S)-hydroperoxy homoallylic alcohols 2 affords the epoxy diol (S,R,S)-4 in high diastereoselectivity (d.r. up to 95:5), while the opticallyactive hydroxy homoallylic alcohols (R,R)-3 are epoxidized by the β-hydroperoxy alcohol 5 under titanium catalysis to the corresponding epoxy (R,S,R)-diol 4 in a diastereomeric ratio up to > 99:1. This high diastereoselectivity