Synthesis of novel cyclohexanediol-derived chiral phosphite ligands and their application in the Cu-catalyzed conjugate addition of organozinc to cyclic enones

A series of novel chiral diphosphite ligands have been synthesized from（1R,2R）-trans-1,2-cyclohexanediol,（1S,2S）-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, and were successfully employed in the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to cyclohexenone with up to 99% ee. It was found that ligand 1,2-bis[（R）-1,10-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a derived from racemic diol skeleton can show similar catalytic performance compared with ligand（1R,2R）-bis[（R）-1,1＇-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a＇ derived from enantiopure starting material. A significant dependence of stereoselectivity on the type of enone and the ring size of the cyclic enone was observed. Moreover, the configuration of the products was mainly determined by the configuration of the binaphthyl moieties of diphosphite ligands in the 1,4-addition of cyclic enones.

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

Functionalized organozinc reagents can easily under 1, 4-addition reaction withunsaturated esters in the presence of catalytic amount of Ni (acac)_2 and tertiary ammes under verymild conditions to give the products in excellent yields.

Hydrotalcite-like Materials as Catalyst for the Conjugate Addition of Amines to Electron Deficient Alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.

A Facile Procedure for Conjugate Addition of Amines to Electron Deficient Alkenes with Metal Oxide as Catalyst

A novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. A series of metal oxides was synthesized for catalyzing the conjugate addition of amines and alkenes. After optimizing the reaction conditions, SrO was chosen as the most efficient catalyst for the reactions. The results show that the catalyst is very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity and applicability to large-scale reactions are the key features of this methodology.

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

Functionalized organozinc reagents can easily conduct 1,4-addition reaction with unsaturated esters in the presence of Cu(OAc)2 and LiCl under very Anld conditions to give the products in excellent yields.

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

A series of enantiomencally pure (4R,5R)-(-)-4-alkryloxy-5-[(1R,2dihydro-2(5H)-furanones (2) have been synthesized in excellent yields via asymmetric conjugateadditions of primary alcohols to (R)-(-)-5-[(1R,2S,5R)-menthyloxy]-2(5H)-furanone (1) in the presenceof a catalytic amount of sodium in DMF, which provides access to new multifunctional homochiralbuilding blocks, optically. pure (R) or (S)-2-alkyloxy- 1,4-butanediols (3).

Ti(IV) Chloride-Promoted Diastereoselective Conjugate Addition of 1-Enoyl-5-substituted Hydantoins with Allyltrimethylsilane

Diastereoselective conjugate addition of 1-enoyl-5-substituted hydantoins with allyltrimethylsilane in the presence of Ti(IV) chloride proceeded to give the corresponding allyl adducts in high yield and high diastereoselectivity. In order to determine the absolute configuration on the β-position of the acyl group, the hydantoin was removed by hydrolysis of the allyl adducts with a base to give the corresponding carboxylic acid. It was found that the absolute configuration was S on the basis of specific rotation.

Conjugate Addition of Indoles to <i>α,β</i>-Unsaturated Ketones Using Bismuth (III) Bromide

An efficient method for the conjugate addition of indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) is reported. Products are isolated by a simple procedure that avoids an aqueous work up and extensive chromatography, thus minimizing waste. Bismuth (III) compounds are especially attractive from a green chemistry perspective because they are remarkably nontoxic, non-corrosive and relatively inexpensive.

Copper-catalyzed conjugate addition of allene-derived nucleophiles to alkenyl-substituted carboxamides

Catalytic Michael addition reaction represents a fundamental importance in organic synthetic chemistry.Whereas corresponding conversions toward intrinsically low reactive enamide remains an ongoing challenging.We herein report a copper-catalyzed conjugate addition of allenes toβ-substituted alkenyl amides,one of the most challenging Michael acceptors.The present method utilizes readily available allenes as the latent carbon-based nucleophiles and simple,commonβ-substituted alkenyl amides as starting materials,unlike previous methods that usually preinstall an activating group to improve the reactivity of amide or uses highly reactive stoichiometric quantities of organometallics.Hence,this approach shows good functional group compatibility and can be implemented under mild reaction conditions with excellent level of chemo-and regioselectivities.

1,6-Conjugate addition of para-quinone methides using gem-diborylcarbanions: Practical access to gem-diborylalkanes bearing vicinal tertiary/quaternary stereocenters

A novel,efficient and pragmatic method to prepare gem-diboron products with vicinal tertiary/quaternary stereocenters using LiTMP-mediated 1,6-conjugate addition of gem-diborylalkanes to para-quinone methides was described for the first time.The results showed that various gem-diboron products with vicinal tertiary and quaternary stereocenters could be formed within 15 min at ambient temperature.This simple protocol has also been applied for the efficient synthesis of the analogue of Bedaquiline.

Asymmetric Photocatalyzed Addition of Cyclic Ammes to the Chiral 5-(l)-Menthyloxy-2(5H)-furanone

The benzophenone-initiated photoaddition of N-methyl ammes 2 to the chiral synthon1 proceeds in a regiospecitlc and highlyr stereocontrolled thshion to give the C-C photoadductscontaining a ne\viy stereogenic center 3a-3c. The enantiomerically pure N-C photoadducts, aminobutenolides 5a-5c have been obtained from the enantioselective photoaddition of secondary cyclicammes 4 with the chiral synthon 1 under the same conditions.

Addition of Organosamarium Reagents toα, β-Unsaturated Esters

Allylsamarium bromide reacts with Q, 6 -unsaturated esters and a -alkyloxy carbonyl α, β-unsaturated esters to give l,2-addition and 1 .4-addition products respectively.

Synthesis of Novel Tartaric Acid-derived Chiral Phosphite Ligands and Their Application in the Cu-catalyzed Conjugate Addition of Diethylzinc to Cyclic Enones

Five novel tropos （3R,4R）- and/or （3S,4S）-N-benzyltartarimide-derived biphenylphosphite ligands were synthesized and applied in the Cu-catalyzed asymmetric conjugate addition of diethylzinc to cyclic enones with up to 75% e.e. Compared with the reported ligand 1-N-benzylpyrrolidine-3,4-bis[（R）-1,1＇-binaphthyl-2,2＇-diyl]phosphite- L-tartaric acid, the issue that L-（＋）-tartaric acid backbone and （R）-binaphthyl showed strong matched/mismatched character was solved with these tropos ligands. It was found that the enantioselectivity was mainly controlled by the absolute configuration of N-benzyltartarimide backbone, and both enantiomers of the addition products can be obtained by simply changing the configuration of N-benzyltartarimide substituent.

Regio-and enantioselective conjugate addition ofβ-nitroα,β-unsaturated carbonyls to construct 3-alkenyl disubstituted oxindoles

Reversal of regioselectivity in the catalytic asymmetric conjugate additions of 3-substituted oxindoles toβ-nitroenones orβ-nitroacrylates was established with chiral scandium catalysts.It enabled the construction of functionalized 3,3-disubstituted oxindoles,including terminal and internal vinyl groups in excellent yields and ee values.

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.

Catalytic conjugate addition of indole toα,β-unsaturated ketones by Co(ClO_4)-2·6H_2O/bis-Schiff base complexes

Co（ClO_4））_2·6H_2O/bis-Schiff base complexes promoted the conjugate addition of indole toα,β-unsaturated ketones under mild conditions,giving the corresponding addition products with high yields.And the complex has been characterized with XRD and IR.

BF_3·Et_2O promoted conjugate addition of ethanethiol to electron-deficient alkynes

An effective method for the synthesis of vinyl thioethers through the conjugate addition of ethanethiol to electron-deficient alkynes promoted by BF3.Et20 has been developed. Electron-deficient internal alkynes react with ethanethiol in this system to yield mainly Z-isomer of vinyl thioether adducts, while electron-deficient terminal alkynes afford mainly E-isomer of vinyl thioether adducts.

Concise synthesis of valuable chiral N-Boc-β-benzyl-β-amino acid via construction of chiral N-Boc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation

Valuable chiral N-Boc-β-benzyl-β-amino acid was concisely synthesized via construction of chiral NBoc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation.All of the starting materials for the synthesis of chiral N-Boc-β-benzyl-β-amino acid are cheap,and two-step short procedure make it easy for the rapid construction of various chiral β-arylmethyl-β-amino acids and important drugs,such as sitagliptin phosphate.

Highly efficient procedure for the conjugate addition of amines to electron deficient alkenes catalyzed by novel ionic liquid

A highly efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.The novel ionic liquid [HO3S-bPy][FeCl4] with both Lewis and Brφnsted acid sites has been synthesized successfully for the reactions.The results show that the catalyst was very efficient for the conjugate addition of amines to electron deficient alkenes with excellent yields in several minutes.This method has several key features including operational simplicity,no need of any solvent,low cost of the catalyst used,high yields,reusability,excellent chemoselectivity,and wide applicability.