摘要:

AbstractReaction of a dialkyl phosphite with a 2‐nitrostyrene in the presence of triethylamine, trimethylsilyl chloride, and hexamethyldisilazane provides a one‐pot procedure for the synthesis of an N‐hydroxy‐indole‐3‐phosphonate and an indole‐2‐one‐3‐phosphonate besides the normal addition product, a 1‐aryl‐2‐ni‐troalkylphosphonate. Such new indole derivatives are difficult to prepare by conventional methods. The ratios of reactant to silylating agent and base were found to have significant influence on the product composition. The mechanism of formation of these het‐er

ISSN:1042-7163    

DOI:10.1002/hc.520030512

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractRates of oxidation of various dithiols with 3‐methyllumiflavin to afford the corresponding cyclic disulfides have been examined at various pH values in 30% aqueous ethanol at 30°C. 1,3‐Propanedithiol, which affords 1,2‐dithiolane, has been found to be the most reactive among several dithiols tested in this oxidation. Kinetic results clearly show that highly strained 1,2‐dithiethanes are formed as primary products in the oxidation of vic‐dithiols with 3‐meth

ISSN:1042-7163    

DOI:10.1002/hc.520030513

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

Abstract(2E)‐α‐Amido‐α,β‐unsaturated sulfones, which are easily prepared by the condensation of α‐amido‐sulfones with aldehydes, can be desulfonylated by sodium hydrogen telluride to give (2Z)‐cinnamanilides with excellent stereoselectivity a

ISSN:1042-7163    

DOI:10.1002/hc.520030514

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe hydroformylation of olefins over rhodium catalysts, with phosphorus ligands added in situ, has been studied under atmospheric pressure. In the case of the Rh4(CO)12cluster, the phosphine‐modified catalyst exhibits very high activity, but there is a decay of catalyst activity with time. The deactivation mechanism of this catalyst has been discussed. In the case of rhodium complexes, Rh(LL′)(CO)2, containing chelate ligands with oxygen and nitrogen as coordinate atoms, the phosphine‐modified catalysts exhibit fairly active activity and very good stability. All these catalysts afford almost 100% chemoselectivity to aldehydes. The regioselectivity is strongly dependent on the nature of the substrate used. The choice of a suitable phosphorus ligand for the catalytic hydrofor‐mylation is dependent on the nature of the rhodium complex used. The effect of phosphorus ligands on the hydroformylation of olefins over rhodium catalysts under normal pressure displays some special features in comparison with that performed under a higher p

ISSN:1042-7163    

DOI:10.1002/hc.520030515

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSilylated enynyl carboxylic esters can be synthesized with high stereoselectivity by the reaction of 3‐trimethylsilyl 2‐propynylidenetriphenylarsorane, generated in situ from the corresponding arsoniunm salt with n‐butyllithium and α‐bromoaceti

ISSN:1042-7163    

DOI:10.1002/hc.520030516

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractDibutyl allylphosphonate can react with palladium chloride to give the dibutyl phosphorylated π‐allylpalladium chloride complex which was found to be able to react with a nucleophile, such as sodium dimethyl malonate, to give a functionalized 1‐alkenyl‐phosphonate. A 1‐acetoxyallylic phosphonate can be regarded as the precursor of a phosphorylated π‐allylic palladium complex in a palladium(O) catalyzed reaction, and the latter reacts with nucleophiles to yield 3‐substituted I‐alkenylphosphonates. The reaction is regioselective. Using this methodology, 3‐aminoalkane‐ and 3‐aminoalkenylphosphonates were synthesized from 1‐acetoxyallylic phosph

ISSN:1042-7163    

DOI:10.1002/hc.520030517

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractA facile and general method for the preparation of diaryltellurium dicarboxylates is described. The method involves simply the stirring of phenyliodine(III) dicarboxylates with diaryltellurides in chloroform at room temperature.

ISSN:1042-7163    

DOI:10.1002/hc.520030518

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSynthesis and reactions of optically active phosphine‐boranes have been investigated. Optically active secondary phosphine‐boranes, (Sp)‐and (Rp)‐menthyloxyphenylphosphine‐boranes, and (S)‐methylphenylphosphine‐borane underwent palla‐dium(0)‐catalyzed electrophilic arylation with o‐, m‐, or p‐iodoanisole. The stereochemistry of this arylation was largely dependent on the solvent and the base used. The reaction in acetonitrile proceeded with almost complete retention of configuration at the chiral phosphorus, whereas inversion of configuration was observed in ethereal solvents or toluene. The phosphorus‐oxygen bond of (Rp)‐menthyloxy (methyl) phenylphosphine‐borane and (SP)‐menthy‐loxy(o‐methoxyphenyl)phenylphosphine‐boranewas reductively cleaved at −78°C by lithium naphtha‐lenide or Li/NH3with virtually net retention of configuration at phosphorus, providing secondary or tertiary phosphine‐boranes in excellent yields. New synthetic routes to optically pure C2‐symmetric bisphosphine‐boranes possessing chirality at phosphorus have been develo

ISSN:1042-7163    

DOI:10.1002/hc.520030519

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

Abstract2‐Methyl‐2‐propanesulfenic acid readily undergoes self‐condensation to give S‐t‐butyl 2‐methyl‐2‐propane‐thiosufinate. Rates of the reaction were measured in aqueous acetonitrile solution by use of NMR and UV spectroscopy. The reaction is second order in the substrate. The half‐life in a neutral aqueous solution is about 150 hours at 35°C when the initial substrate concentration is 0.003 M. The rate is proportional to acid concentration in the range 0.004–0.2 M. In alkaline solution, the main reaction is self‐condensation but some side reactions also seem to occur. The disappearance of the substrate does not follow satisfactory second‐order kinetics, but the second‐order rate constants obtained by the time‐lag method show a maximum around pH 10–11. The pKa(10.47) of the sulfenic acid was obtained at 14°C from a sig‐moid curve of the initial absorbances (240 nm) determined by extr

ISSN:1042-7163    

DOI:10.1002/hc.520030520

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractAn efficient and mild reaction for introducing an allylic moiety and an alkylthio‐ or alkylseleno‐group onto the α‐carbon of β‐dicarbonyl compounds in one step by tandem transylidation and [2,3]‐sigmatropic rearrangement i

ISSN:1042-7163    

DOI:10.1002/hc.520030521

出版商:VCH Publishers, Inc.    

年代:1992

数据来源: WILEY