ISSN:0165-0513    

DOI:10.1002/recl.19951140402

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractXylene oxygenase (XO), an enzyme system fromPseudomonas putidamt‐2, selectively oxidizes the methyl side group of toluene‐derived compounds. The enzyme is related toPseudomonas oleovoransmono‐oxygenase (POM), which has been used to produce optically active epoxides from various alkenes at high enantiomeric excess.We have introduced XO intoEscherichia coliand produced variously substituted benzyl alcohols from toluene derivatives and optically active styrene epoxides from styrene,m‐andp‐chlorostyrene andm‐andp‐methylstyrene using this biocatalyst. The products of oxidation of styrene and styrene derivatives had enantiomeric excesses(ees) ranging from 37% to over 98%.Similarly,Pseudomonas putidawas engineered such that the hydroxylation of compounds by POM could be investigated independent of subsequent product degradation. The biocatalyst accepted a wide range of substrates and oxidized both linear and branched alkanes, and cyclic alkanes as well as alkylbenzenes to the corresponding alcohols.In this review we describe the catalytic potential of engineered biocatalysts based on both XO and POM and discuss the structural and functional similarities of these non‐heme iron

ISSN:0165-0513    

DOI:10.1002/recl.19951140403

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractChiral (enantiomerically pure) hydrogen thiophosphoramidates and hydrogen phosphoramidates and their phosphinamide analogs derived from norephedrine and other chiral (enantiomerically pure) amino alcohols catalyze the enantioselective addition of dialkylzines to aldehydes. The presence of titanium tetraisopropoxide increases the enantioselectivity, providing enantiomerically enriched secondary alcohols with up to 98%ee.The enantioselectivities of thiophosphoramidates and thiophosphinamides are higher than those of the oxygen analogs. The phosphoramidates and thiophosphoramidates, without the hydroxyl group, also catalyze the addition of dialkylzinc to aldehydes in the absence of Ti(OiPr)4.

ISSN:0165-0513    

DOI:10.1002/recl.19951140404

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractSolenopsins A, B and C have been synthesized in enantiomerically pure forms from the correspondinganti‐1,5‐diols which have been obtained from glutaric anhydride by an asymmetric synthesis induced by chiral sulfoxi

ISSN:0165-0513    

DOI:10.1002/recl.19951140405

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe circular dichroism (CD) and UV spectra of chiral bridged aromatic compounds, 7,8,15,16−tetrahydro‐7,15‐methanocycloocta[1,2‐a:5,6‐a′]dinaphthalene‐8,16 ‐diol [(‐)‐1]and −8,16‐ dione [(‐)‐2], have been theoretically calculated by application of the π‐electron self‐consistent‐ field‐configuration‐interaction‐dipole‐velocity molecular orbital (SCF‐CI‐DV MO) method. The shape of component CD and UV bands was approximated by the Gaussian distribution method (A), or by employing the observed band shape of the UV spectra of model compounds (method B). The calculated CD and UV curves were in good agreement with the observed ones. For compound(7S,8R,15S,16R)‐(‐)‐1, method A: calcd. CD, λext237.0 nm (Δϵ−319.2), 224.2 (+ 344.9),A= −664.1; obsd. CD, λext233.0 nm (Δϵ−671.0), 222.3 (+ 194.6),A= −865.6. The calculated CD and UV spectral curves of compound 1 obtained by the application of method B were in excellent agreement with the observed ones: calcd. CD, λext233.6 nm (Δϵ−740.8), 222.2 (+ 265.0),A= −1005.8; obsd. CD, λext233.0 nm (Δϵ−671.0), 222.3 (+ 194.6),A= −865.6. For compound (7S,15S)‐(‐)‐2, method A: calcd. CD, λext256.4 nm (Δϵ−69.4), 220.3 (+ 103.5); obsd. CD, λext254.4 nm (Δϵ−89.0), 217.0 (+ 222.1). The

ISSN:0165-0513    

DOI:10.1002/recl.19951140406

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe synthesis, spectral characteristics, and X‐ray structures for dirhodium(II) tetrakis[methyl 2‐oxooxazolidin‐4(S)‐carboxylate], Rh2(4S‐MEOX)4, and the related dirhodium(II) tetrakis[methyl 5(R)‐methyl‐2‐oxooxazolidin‐4(S)‐carboxylate], Rh2(4S‐THREOX)4, are reported. Comparison is made between these 2‐oxooxazolidin‐ligated dirhodium(II) catalysts for metal carbene transformations and those with comparable 2‐oxopyrrolidine ligands, especially dirhodium(II) tetrakis[methyl 2‐oxopyrrolidine‐5(S)‐carboxylate], Rh2(5S‐MEPY)4. Structure‐selectivity comparisons reveal that Rh2(4S‐MEOX)4provides higher enantiocontrol and, in some cases, higher diastereocontrol than Rh2(5S‐MEPY)4in intramolecular carbon‐hydrogen insertion reactions of sterically demanding diazoacetates and diazoacetamides and is the catalyst of choice for highly enantioselective diazodecomposition of adamantyl diazoacetates andN‐(tert)butyldiazoacetamides. The structurally analogous Rh2(4S‐THREOX)4is nearly identical with Rh2(4S‐ MEOX)4in its overall effect on selectivity. The net advantage of Rh2(4S‐MEOX)4lies in i

ISSN:0165-0513    

DOI:10.1002/recl.19951140407

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe ammoniolysis of amino acid esters and their derivatives was performed with lipases and proteases yielding the corresponding amino acid amides with moderate to high enantioselectivity. Phenylglycine methyl ester racemized slowly under the reaction conditions.

ISSN:0165-0513    

DOI:10.1002/recl.19951140408

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe alkylation reactions of enolates derived from the highly diastereoselective conjugate additions of lithium (R)‐N‐benzyl‐N‐α‐methylbenzylamide(R)‐1 toN, N‐dimethyl crotonamide2andN, N‐dimethyl cinnamide3have been investigated. The alkylations of enolates derived from 3 are shown to affordanti‐α‐alkyl‐β‐amino carboxamides with excellent stereocontrol: the stereochemistry is assigned with the aid of a single crystal X‐ray structure of(2R,3S,αR)‐N, N‐dimethyl 2‐benzyl‐3‐phenyl‐3‐(N‐benzyl‐N‐α‐methylbenzylamino)propanamide(2R,3S,αR)‐10. As a result of the difficulty encountered in hydrolysing these hindered β‐amino amides such as10, an alternative procedure is developed involving conjugate addition‐alkylations with α,β‐unsaturated N‐acyloxazolidin‐2‐ones as substrates, giving sele

ISSN:0165-0513    

DOI:10.1002/recl.19951140409

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA range of rigid, architecturally complex diols derived from dispiroketals have been synthesised. A bifunctional,C2‐symmetrical, chiral auxiliary derived from these dihydroxylated dispiroketals has been used to induce a high degree of asymmetry in Michael additions of cuprates to a variety of di‐α, β‐unsaturated ester

ISSN:0165-0513    

DOI:10.1002/recl.19951140410

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractTricarbonylchromium(0) complexes of sulfur, phosphorus, silicon, iodine, tin and carbon substituted(S)‐(α‐methylbenzyl)dimethylamines are oxidized by dimethyldioxirane to enantiomerically pure tricarbonylchromium(0) complexes of substituted styrenes; the reactions proceed via a chemoselective oxidation of the tertiary amines to theirN‐oxides, one of which was isolated, and a subsequent Cope re

ISSN:0165-0513    

DOI:10.1002/recl.19951140411

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY