碱促进联烯酮与丙酮二羧酸酯反应制备官能化的2-羟基间苯二甲酸酯

发展了一种以碳酸钾为碱,在温和条件下,通过1,2-联烯酮与丙酮二羧酸二乙酯的串联反应高效合成取代2-羟基间苯二羧酸二乙酯类化合物的新方法。在最优条件下,以73%~85%的收率成功合成了一系列的目标产物。从机理上而言,该方法涉及了联烯酮与活泼亚甲基化合物的共轭Michael加成和酮的分子内羟醛缩合两个反应的串联组合。与文献方法相比,该方法还具有简单的起始原料,极高的反应产率和方便的处理过程等优点。     

Ru(III)-catalyzed oxidation of homopropargyl alcohols in ionic liquid: an efficient and green route to 1,2-allenic ketones

An efficient and environmentally benign synthesis of 1,2-allenic ketones via RuCl₃-catalyzed oxidation of homopropargyl alcohols in ionic liquid with tert-butyl hydroperoxide (TBHP) as the oxidant was reported for the first time. With its reasonable efficiency and green nature, this oxidation provides a novel alternative route to 1,2-allenic ketones.     

Highly regioselective and practical synthesis of 1-acyl-5-hydroxypyrazolines and 1-acyl pyrazoles from 1,2-allenic ketones and hydrazides

A mild and highly regioselective synthesis of 1-acyl-5-hydroxypyrazolines has been achieved through the condensation of 1,2-allenic ketones with hydrazides in the absence of any catalyst. Moreover, the obtained 1-acyl-5-hydroxypyrazolines can be easily transformed into 1-acyl pyrazoles under the promotion of BF₃·Et₂O. It was also found that 1-acyl pyrazoles can be produced directly from allenic ketones and hydrazides through a one-pot procedure.     

Synthesis of cyclopentenyl and cyclohexenyl ketones via [3 + 2] and [4 + 2] annulations of 1,2-allenic ketones简

In this paper, an efficient synthesis of cyclopentenyl ketones and cyclohexenyl ketones through tertiary phosphine catalyzed [3 ＋ 2] and [4 ＋ 2] annulations of 1,2-allenic ketones with activated alkenes has been developed. Compared with published synthetic methods on cyclopentenyl ketones and cyclohexenyl ketones, the protocols developed in this paper have the advantages such as readily available starting materials, mild reaction conditions and high efficiency.     

Studies on K2CO3-catalyzed 1,4-addition of 1,2-allenic ketones with diethyl malonate: controlled selective synthesis of beta,gamma-unsaturated enones and alpha-pyrones

The K2CO3 (10 mol %)-catalyzed 1,4-addition reaction of diethyl malonate with various substituted 1,2-allenic ketones leading to polyfunctionalized beta,gamma-unsaturated enones 3 or 4 was studied. With 3-unsubstituted 1-substituted-1,2-allenyl ketones, the highly selective formation of beta,gamma-unsaturated enones 4 was observed; with 1,2-allenyl ketones bearing one or two 3-substituents in the allenyl group, only beta,gamma-unsaturated enones 3 with an unmigrated carbon-carbon double bond were produced; with 3-monosubstituted-1,2-allenyl ketones Z-beta,gamma-unsaturated enones 3 were formed with excellent stereoselectivity (E:Z > 96:4); with propadienyl ketones, mixtures of beta,gamma-unsaturated enones 3 and 4 were formed. alpha-Pyrone derivatives were synthesized via the K(2)CO(3)-catalyzed or -promoted reaction of 1,2-allenic ketones with diethyl malonate via a sequential Michael addition-carbon-carbon double bond migration-lactonization process.     

Enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via β-elimination/cycloaddition sequence

A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities (85%–98% ee and 84%–95% ee, respectively).     

Tandem reactions of 1,2-allenic ketones leading to substituted benzenes and α,β-unsaturated nitriles

One-pot double Michael addition/intramolecular aldol reaction/decarboxylation of 1,2-allenic ketones with cyanoacetate offers an efficient and convenient approach to highly functionalized benzenes. With 2-substituted cyanoacetates, the reaction proceeds via a different tandem process to afford α,β-unsaturated nitriles effectively.     

New preparation of α-allenic ketones

The ketal aldehyde 2 is the starting material of a two-step synthesis of α-allenic ketones 1 γ-substituted with a functionalized chain.     

1，2－联烯亚砚和1，2－联烯砜的反应

1，2－联烯亚砜和1，2－联烯砜是重要的含硫联烯化合物，综述了1，2－联烯 亚砜和1，2－联烯砜的亲核加成、亲电加成、Diels-Alder反应、1，3－偶极加成 、[2+2]环加成等反应以及在天然产物中的应用。     

1,2‐Thiazines: One‐Pot Syntheses Utilizing Mono and Diaza Analogs of Sulfones

A one‐pot Michael addition/cyclization/condensation reaction sequence for the regioselective synthesis of 1,2‐thiazines, starting from propargyl ketones and NH‐sulfoximines or NH‐sulfondiimines, has been developed. Under mild and operationally simple reaction conditions previously unprecedented 1,2‐thiazine 1‐imide and 1‐oxide derivatives are formed in good to excellent yields. The products represent heterocyclic building blocks, readily modifiable by a regioselective C?H bond functionalization, classical cross‐coupling reactions, and deprotection.     

Catalyst-free alkanoylation of aromatic rings via arylstannanes. Scope and limitations

The reaction of alkanoyl chlorides with arylstannanes in 1,2-dichlorobenzene (180 °C) is a simple and direct route for the catalyst-free and regioselective synthesis of tertiary alkyl aryl ketones in good to excellent isolated yields (55-77%). Nevertheless, under similar conditions, reactions carried out with alkanoyl chlorides bearing α-hydrogens render only the product of protodestannylation.     

One pot three-component regioselective and diastereoselective synthesis of halogenated pyrido[2,1-b][1,3]oxazines

Three-component reactions of 3-substituted pyridines, dimethyl acetylenedicarboxylate (DMAD), and α-halo ketones led to regioselective and stereoselective synthesis of pyrido[2,1-b][1,3]oxazines in high to excellent yields under mild conditions. All the reactions gave the pyrido[2,1-b][1,3]oxazine derivatives without formation of any indolizine products.     

Synthesis of β-fluoroenones and their reductive rearrangement in aqueous media

In this paper, a simple and efficient preparation of β-fluoroenones, as a mixture of E/Z isomers with the E-isomer as the main product, from 1,2-allenic ketones by using TBAF·3H₂O in water as a nucleophilic fluorination agent has been developed. Moreover, in exploring the synthetic applications of β-fluoroenones, an unprecedented reductive defluorination rearrangement of β-fluoroenones toward enones under mild conditions in aqueous media was also discovered.     

1,2-联烯基酮的合成与反应

1,2-联烯基酮可以通过2-丙炔基酮异构化反应,相应有机金属试剂中间体与酯、酰氯或酰胺的反应,[2,3]或[3,3]迁移反应,Wittig反应,消除反应,2,3-联烯醇氧化等方法合成。由于联烯酮上含有吸电子基团羰基,它可发生亲核加成、环加成、环化反应。     

New reactions of alkynes with ketones in superbasic media

The present work reviews new reactions of alkynes with ketones in the superbasic media MOH—DMSO (M = Na, K, Cs) and KOBu^t—DMSO: the stereoselective nucleophilic addition of deprotonated ketones to the triple bond to form the E-isomers of β,γ-enones; vinylation of tertiary acetylenic alcohols that formed in situ from acetylene and ketones; the direct synthesis of vinyl ethers of tertiary acetylenic alcohols from acetylene and ketones; the stereoselective synthesis of dispirocyclic ketals containing the Z-ethylene fragment from arylalkynes and two molecules of a cyclic ketone; the stereoselective cascade synthesis of hexahydroazulenones from two arylalkyne molecules and 2-alkylcyclohexanones; the stereoselective cascade assembly of 7-methylidene-6,8-dioxabicyclo[3.2.1]octanes from two acetylene molecules and two ketone molecules; the stereoselective cascade synthesis of 7-methylidene-6,8-dioxabicyclo[3.2.1]octanes from acetylenes and 1,5-diketones; and the three-component cascade reaction of acetylene, ketones, and oximes to afford 4-methylidene-3-oxa-1-azabicyclo-[3.1.0]hexanes.     

Studies on t-BuOK-catalyzed Michael addition of 1,2-allenic ketones with 2-substituted diethyl malonates: highly selective synthesis of β,γ-unsaturated enones

In this paper, we have demonstrated a facile nucleophilic addition of 2-substituted diethyl malonate to various substituted 1,2-allenic ketones to afford β,γ-unsaturated enones using a catalytic amount of t-BuOK as the base. The reaction usually completes within 10 min in acetone at room temperature. The stereoselectivity of the reaction with γ-substituted allenic ketones is very high affording the β,γ-unsaturated E-enones.     

A substituent-controlled general approach to access arylated pyran-2-ones and pyrano[3,4-c]pyran-1,8-diones

2H-Pyran-2-ones are useful precursors for the synthesis of various aromatic and heterocyclic compounds. In this Letter, we describe substituent-controlled direct access to functionalized 4-(2-oxo-1,2-diarylethyl)-5,6-diaryl-pyran-2-ones by stirring a mixture of 3-cyano-5,6-diaryl-2H-pyran-2-ones and functionalized deoxybenzoins through an unusual decyanation reaction. Under similar reaction conditions, the reactions of 3-carbomethoxy-5,6-diaryl-2H-pyran-2-ones with either substituted acetophenones or deoxybenzoins led to the synthesis of pyrano[3,4-c]pyran-1,8-diones in excellent yields.     

Vicinal difunctionalization of dehydropiperidines using α-chloro-β-sulfonyl eneformamides

The synthesis of α,β-difunctionalized dehydropiperidines has been accomplished using α-halo-β-sulfonyl eneformamides. This outcome is achieved through sequential regioselective C_β-alkylative desulfonation and C_α-palladium-catalyzed cross-coupling. In most cases, high yields of the vicinally functionalized eneformamides are obtained.     

Regioselective addition of 1,3-dicarbonyl dianion to N-sulfonyl aldimines: an expedient route to N-sulfonyl piperidines and N-sulfonyl azetidines

A simple route for the synthesis of δ-amino-β-keto esters and δ-amino-β-diketones is reported. This involves regioselective addition of 1,3-dianions derived from ethyl acetoacetate and acetyl acetone to N-sulfonyl aldimines. The δ-amino-β-keto ester derivatives were further converted into the corresponding N-sulfonyl piperidines and N-sulfonyl azetidines.