Conjugate Addition Reactions of Functionalized Organozinc-copper Reagents to α,β-Unsaturated Esters

Theconjugateadditionoforganometal1icstoMichaelacceptorsisanimportantsyntheticmethodforcarbon-carbonbondformation'.FunctionalizedorganozincreagentsaremoreusefulinthatfleldbecausetheytolerateabroadrangeoffunctionalitiesandreactinthepresenceofCuCN'2LiClwithvariouselectrophilesinexcellentyields"'.Thus,apolyfunctionalizedorganicmoleculecanbeformedinonestep.However,CuCNhasbeentheonlycoppersaltsinceitwasfirstusedinl988,',andunsaturatedestersdonotreactwithfunctionalizedorganozincreagentsundergener…     

Nickel (Ⅱ) Complex Catalyzed Conjugate Addition Reaction of Functionalized Organozinc Reagents to α,β-Unsaturated Esters

Functionalizedorganozinchandes(FG-ZnX)haveprovedtobeveryusefulinorganicsynthesisinrecentyears'.Theycanalsobesuccessfullyusedinconjugateadditionreactionswithcarbonylcompounds'.However,stoichiometriccoppersaltCuCN'ZLiCImustbeusedinmostcasesl'2andunsatu...     

Michael Additions of Activated Methylene Compounds to α,β-Unsaturated Esters Promoted by Samarium (Ⅲ) Iodide

IntheIastdecadestheapplicationsofsamariumreagentsinorganicsynthesishavebeenrapidlyincreasedl-6.CatalyzedbySm(OTO,benzyIaminecanaddtoethylcrotonatetoformD-aminoesters=;attheaidofSm(OTfl,ands-BuLimethyliodidehasbeenaddedtocarbonylgroupofacetophenone';WehavereportedthatpromotedbySml,a-haloketonescanreactwithaldehydestogiveQ,6=unsaturatedketones4.VeryrecentlywefoundthatD-diketonescanbesynthesizedviareactionofa-haloketoneswithacidchloridesoracidanhydridesattheaidofSmI=orSmI,'.Wealsoreported…     

One-pot Approach to the Conversion of Alcohols into α-Halo-α,β-unsaturated Esters

α-Halo-α, β-unsaturated esters are important intermediates in organic synthesis. For example, they are used for α-amino acid preparation1 and vinylogous Darzen reactions2, as a versatile fluorinated building block, they are also used for the preparati…     

Stereoselective Addition of N-Alkylhydroxylamines to α,β-Unsaturated Nitro Compounds

Since Baldwin reported that the addition of N-substituted hydroxylamines to α,β-un- saturated ester is a general procedure for the synthesis of isoxazolidin-5-ones1, the conjugate addition of N-alkylhydroxylamines to α,β-unsatutated esters2-4, lactone…     

Reaction of Grignard Reagents with Diethyl Perfluoroacyl (1-Cyanoethyl)phosphonates. Synthesis of Perfluoroalkylated α,β-Unsaturated Nitriles with Predominant Z-Selectivity

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｄｅｖｏｔｅｄｔｏｔｈｅｓｙｎｔｈｅｓｉｓｏｆα ,β ｕｎｓａｔｕｒａｔｅｄｎｉｔｒｉｌｅｓｓｉｎｃｅｔｈｅｙａｒｅｉｍ ｐｏｒｔａｎｔｓｔｒｕｃｔｕｒａｌｆｅａｔｕｒｅｏｆｓｅｖｅｒａｌｎａｔｕｒａｌｌｙｏｃｃｕｒｒｉｎｇｂｉ ｏｌｏｇｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ .1,2 Ｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｆｌｕｏ ｒｉｎｅｏｒｔｒｉｆｌｕｏｒｏｍｅｔｈｙｌｇｒｏｕｐｉｎｔｏｂｉｏｌｏｇｉｃａｌｌｙａｃｔｉｖ…     

Stereocontrolled Synthesis of (E)-β,γ-Unsaturated Esters via Palladium-Catalyzed Cross-Coupling of (E)-Alkenylboronic Acids with α-Bromoacetic Esters

The cross-coupling reaction of trans-alkenylboronic acids with a-bromoacetic esters was firstly studied. It was found that using Pd(OAc)2 as catalyst, a bulky electron-rich phospine, (2-dicyclohexylphospino-biphenyl) as ligand, the reaction can be readily accomplished to give specific (E)-b,g-unsaturated esters in high yields.     

含硫碳负离子的反应及其应用的研究 II: 固-液相转移催化共轭加成作用

亲核性的碳负离子与亲电性碳-碳重键的共轭加成反应是构成新碳-碳键的重要方法。某些α-亚磺酰基碳负离子虽然也能与α,β-不饱和酯进行共轭加成,但要有效地产生这类含硫碳负离子往往要用对潮气敏感的强碱性试剂,如氢化钠等。最近,我们报告了在固-液相转移催化条件下α-苯亚磺酰基乙酸甲酯(1)的碳负离子的     

Highly Efficient InBr3 Catalyzed Michael Addition of Indoles to α, β-Unsaturated Esters

A highly efficient synthetic strategy toward Michael addition of indoles to α,β‐unsaturated esters has been developed using Lewis acid InBr₃ as catalyst. The reactions generated 3‐substituted indoles in high yields with excellent regio‐selectivity in the presence of catalytic amount of InBr₃ under mild reaction conditions. The method is simple, efficient and practical.     

Conjugate Addition of Alkyllithium Reagents to α,β-Unsaturated N,N',N'-Trimethylhydrazides

The site of nucleophilic attack by an alkyllithium reagent upon an α,β-unsaturated carbonyl compound is governed by, among other factors, the nature of the group attached to the carbonyl.¹ Thus the amount of carbonyl addition decreases in favor of conjugate addition for the α,β-unsaturated series: aldehyde, ketone, ester, amide. We wish to report that α,β-unsaturated carboxylic acid trimethylhydrazides, which have an exceptionally unreactive carbonyl group², undergo exclusive conjugate addition with simple alkyllithium reagents.³ Furthermore, the derived hydrazide lithium enolates can be transformed in convenient and useful ways.     

The Michael Addition of Sulfur Anions to β,β-Substituted Nα-Formyl-α, β-Dehydroamino Acid Esters

The addition of lithium benzylthiolates to N^α,-formyl-α,β-dehydro-α-amino acid esters gave protected N^α-formyl-β-S-benzyl-β,β-dialkylcysteine esters. Hydrolysis and N^α-protection produced β,β-dialkyl-cysteines which can be used for peptide synthesis.     

Conjugate Addition of Indoles to α, β-Unsaturated Ketones （Chalcones） Catalyzed by KHSO4 under Ultrasonic Conditions

Conjugate addition of indoles to a variety of α,β-unsaturated ketones （chalcones） mediated by a catalytic amount of KHSO4 at room temperature under ultrasonic conditions to afford the corresponding Michael adducts in good to excellent yields was reported.     

Highly selective hydrohalogenation reaction of substituted 2,3-allenoates

The hydrohalogenation reaction of 1-alkyl substituted 1,2-allenyl carboxylic acid esters (1) with MX (M= Na, or Li, X= Cl, Br, I) afforded a mixture of (5,7-unsaturated 3-halo-3-alkenoates (2) and α,β-unsaturated 3-halo-2-alkenoates (3) in HOAc, while using a mkture of HOAc-CF3CO2H (1:1) or CF3CO2H as the reaction medium the corresponding reaction cleanly produced β,γ-unsaturated 3-halo-3-alkenoates (2) as the sole products in high yields. The subsequent coupling reactions were studied.     

Lewis Acid Mediated Addition of Aminoketene Dithioacetals to α, β-Unsaturated Ketones

Lewis acids catalyse the addition of aminoketene dithioacetals to α-β-unsaturated ketones to give 1,5-diketones after hydrolytic work-up.     

Enantioselective addition of Et_2Zn to aldehydes catalyzed by chi-ral aliphatic β-amino alcohols

This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonanol (1b). They were synthesized by methylation of the corresponding β-amino alcohols 2a and 2b. Compounds la and 1b catalyze the addition of diethylzinc to various aldehydes enantioselectively. The catalyst structure-enantioselectivity relationships were discussed.     

Ceric Ammonium Nitrate-mediated Oxidative Cycloaddition of 1,3-Dicarbonyls to β-Aryl-α,β-unsaturated Ketones

Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by ceric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.     

Study on Nucleophilic Additions to endo-tricyclo[5.2.1.0~(2,6)]deca-2(6),8-dien-3-one and an Unusual Payne Rearrangement of α,β-Epoxy Tricyclodecenone

The facial selectivity of nucelophilic additions to endo-tricyclo [5.2.1.02,6] deca-2(6),8-dien-3-one 1 demonstrates a high preference for exo-facial attack to the enone moiety1. We were interested in whether it would be possible to accomplish three-ring annulation to tricyclodecenone 1 by cyclopropanation or epoxidation. Three-ring annulation would lead to an increase in total ring strain as compared with the starting enone, not as previous nucleophilic addition reactions which release strain…     

SmI2－Mediated Addition Reaction of α－Halomethylsulfones to Carbonyl Compounds. A Convenient Synthesis of β－Hydroxysulfones

Due to the chemoselective dehalogenation by SmI2, the addition of a-halomethylsulfones to carbonyl compounds afforded ,β-hydroxysulfones. Those reactions with α-bromomethylsulfones gave the products in moderate to good yields. The SmI2-mediated addition of gem-dihalomethylsulfones to ketones also afforded α-halo-β-hydroxysulfones in moderate yields.     

[Bmim]OAc Catalyzed Michael Addition of Active Methylene to α,β-Unsaturated Carboxylic Esters and Nitriles

<正>Michael addition of active methylene compounds toα,β-unsaturated carboxylic esters and nitriles was effectively catalyzed by a basic ionic liquid,1-butyl-3-methylimidazolium acetate([Bmim]OAc).The bis-addition products were selectively obtained in high yields under miLd reaction conditions.