Complementary enantiospecific syntheses of conduritol E epoxides from halobenzenes
摘要:
Microbial oxidation of chlorobenzene or bromobenzene gave diols (3), which were converted in stereoselective and chemoselective sequences involving epoxidation/osmylation steps and reduction to the enantiomers of (-)- or (+)-conduritol E epoxide (4).
Enantiopure arene dioxides: chemoenzymatic synthesis and application in the production of trans-3,4-dihydrodiols
作者:Derek R. Boyd、Narain D. Sharma、Colin R. O’Dowd、Francis Hempenstall
DOI:10.1039/b006837n
日期:——
Enantiopure syn- and anti-arene dioxides are
synthesised from cis-dihydrodiol metabolites;
anti-benzene dioxides are reduced to enantiopure
trans-3,4-dihydrodiols while syn-benzene dioxides
racemise thermally via 1,4-dioxocins.
作者:Timothy J. Donohoe、Peter R. Moore、Michael J. Waring、Nicholas J. Newcombe
DOI:10.1016/s0040-4039(97)01061-7
日期:1997.7
The preparation and dihydroxylation of a series of polyenes and cyclicallylicalcohols using the TMEDA/osmium tetroxide mixture is reported. Remarkably, these reagents lead to high levels of regiochemical and stereochemical control as the oxidant hydrogen-bonds to the allylicalcohol group. A mechanistic hypothesis is presented which invokes the formation of a reactive, bidentate complex between osmium
Directed Dihydroxylation of Cyclic Allylic Alcohols and Trichloroacetamides Using OsO<sub>4</sub>/TMEDA
作者:Timothy J. Donohoe、Kevin Blades、Peter R. Moore、Michael J. Waring、Jon J. G. Winter、Madeleine Helliwell、Nicholas J. Newcombe、Geoffrey Stemp
DOI:10.1021/jo026161y
日期:2002.11.1
The oxidation of a range of cyclicallylicalcohols and amides with OsO4/TMEDA is presented. Under these conditions, hydrogen bonding control leads to the (contrasteric) formation of the syn isomer in almost every example that was examined. Evidence for the bidentate binding of TMEDA to OsO4 is presented and a plausible mechanism described.
Catalytic double osmylation is described for a series of cyclohexadienes in acetone/H2O in the presence of the co-oxidant N-methylmorpholine N-oxide (NMO). The formation of polyols occurred stereospecifically with cyclohexadienes 3,7, and 11a, leading thereby to tetrols 5a, and 9a and to allo-inositol (14a), respectively. To the contrary, trans-cyclohexadiene-diol 15a gave a mixture of the stereoisomeric
描述了在共氧化剂N-甲基吗啉N-氧化物(NMO)存在下在丙酮/ H 2 O中的一系列环己二烯的催化双渗透作用。多元醇的形成与环己二烯立体有择发生3,7,和11a中,从而导致四醇5A,以及图9a和同种异体肌醇(14A分别地)。相反,反式-环己二烯二醇15a给出了立体异构肌醇18a(epi),19a(neo)和20a(手电筒)。高场NMR使多羟基化衍生物的构象分析更加清晰。
A Novel Synthesis of Conduritol-C and Conduritol-E via p-Benzoquinone
Abstract A new and stereospecific synthesis for Conduritol-C 8 and Conduritol-E 13a has been developed starting from p-benzoquinone 1. 1,4-oxygen functionalities were introduced in both synthesis by the reduction of dibromo p-benzoquinone 2 with NaBH4. 2,3-oxygen functionalities were introduced by KMnO4 oxidation of 4 for Conduritol C 8. Oxidation of 3 with m-chloroperbenzoic acid gave 9. Acid-catalyzed