One-step synthesis of thiazolo[3,2-a]pyridines by a multicomponent reaction of β-enaminonitriles, α,β-unsaturated aldehydes, and 2-aminothiol hydrochlorides

A wide library of 3,7,8,8a-tetrahydro-2H-thiazolo[3,2-a]pyridines has been prepared by simple heating in acetonitrile of β-enaminonitriles, α,β-unsaturated aldehydes and 2-aminothiol hydrochlorides. Chemical yields depend on the nature, hindrance, and position of the substituents. The scope, limitations, and stereocontrol associated to this three-component reaction have been studied in detail. In general, the diastereoinduction observed in the three new stereogenic centers generated in the pro-chiral α,β-unsaturated aldehyde is low.     

Organocatalytic oxy-Michael addition of alcohols to α,β-unsaturated aldehydes

1,4-Addition of alcohols to α,β-unsaturated aldehydes was found to be efficiently promoted by biphenyldiamine-based catalyst 3 without formation of the acetals.     

Transition metal-catalyzed formation of CF3-substituted α,β-unsaturated alkene and the synthesis of α-trifluoromethyl substituted β-amino ester

A new transition metal-catalyzed formation of CF₃-substituted α,β-unsaturated alkenes through the ylide intermediate from the reaction between methyl 3,3,3-trifluoro-2-diazopropionate 1 and aryl aldehydes has been developed. Further transformation of the alkene affords the α-trifluoromethyl substituted β-amino ester, a valuable intermediate in the synthesis of fluorine-containing amino acids with potential biological application.     

关于Ext代数生成次数的界的一个注记

为了研究分次代数的Yoneda代数的有限生成性,Green和Marcos于2005年引进了δ-Koszul代数的概念并提出了三个公开问题.本文通过讨论分段Koszul代数的相关性质,给出了第三个问题的答案.     

BrΦnsted酸性离子液体[HSO3-bpy][HSO4]催化合成β-吲哚酮

以BrΦnsted酸性离子液体[HSO3-bpy][HSO4]为催化剂, 将吲哚或取代吲哚与α,β-不饱和酮在乙腈中于80 ℃下反应3 h, 以92%～98%的产率制备了一系列的β-吲哚酮. 该方法简便易行且产率高. 催化剂离子液体对环境友好, 并可循环使用.     

First synthesis of 1-aryl-4,4-dichlorobut-3-en-1-ones. The electrochemical reduction of 1-aryl-4,4,4-trichlorobut-2-en-1-ones as a key step

The first method for the synthesis of 1-aryl-4,4-dichlorobut-3-en-1-ones is reported. Treatment of acetophenones with anhydrous chloral leads to 1-aryl-4,4,4-trichloro-3-hydroxybutan-1-ones in near quantitative yields. These compounds were efficiently dehydrated with either sulfuric or p-toluenesulfonic acid to give 1-aryl-4,4,4-trichlorobut-2-en-1-ones, which were selectively converted to the title compounds in fair to quantitative yields by electrochemical reduction. The X-ray crystallographic structure of 4,4-dichloro-1-(4-methoxyphenyl)but-3-en-1-one has been determined. The preferential formation of β,γ-unsaturated ketones with total exclusion of the corresponding α,β-unsaturated isomers has been discussed with the aid of HF and B3LYP density functional theory methods.     

Nucleophilic Addition to (η3-Allyl)Fe(CO)4 Cations with Functionalized Zinc-Copper Reagents RCu(Znl)CN

Regioselectivity of the addition of the highly functionalized zinc-copper reagents to (η³-allyl)Fe(CO)₄ cationic salts was studied. For 1,1-disubstituted allyl cation 1, the zinc-copper reagents added predominantly at the unsubstituted terminus. For 1,1,2-trisubstituted allyl cation 2, reactive zinc-copper reagents attacked mainly at the unsubstituted terminus while less reactive zinc-copper reagents added to a coordinated CO ligand. For 1,1,3-trisubstituted allyl cation 3, the addition occurred at both the less substituted allyl terminus and a coordinated CO ligand.     

Oxidation of Tricarbonyl (η1 η2-but-3-en-1-yl)iron(0)and Tricarbonyl (η3-allyl)iron(0) Anion Complexes with Dioxygen

The addition of reactive carbanions to tricarbonyl(η⁴-1,3-diene)iron(0) complexes proceeded at ?78 °C to give putative tricarbonyl(η¹,η²-but-3-en-1-y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η³-allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ-unsaturated acids and allylic alcohols, respectively.     

A one-pot synthesis of polysubstituted imidazo[1,2-a]pyridines

A series of 5,7,8-polysubstituted imidazo[1,2-a]pyridines were synthesized regioselectively from in situ generated α,β-unsaturated imines and dianions derived from methyl azolyl acetates in a one-pot procedure. The targeted molecules were conveniently isolated in analytically pure form (ca. 50-70% yields) by trituration of the concentrated reaction mixtures with cold ether.     

Novel one pot synthesis of polysubstituted pyrazolo[1,5-a]- and imidazo[1,2-a]pyrimidines

We have described a convenient regioselective one-pot approach to pyrazolo[1,5-a]- and imidazo[1,2-a]pyrimidine derivatives from α,β-unsaturated imines generated in situ and amino heterocycles. Reaction is general with respect to all three components, namely (i) nitrile, (ii) aldehyde, and (iii) amino heterocycle reagents. Good yields (52-77%), convenient isolation of the targeted molecules are the distinct characteristics of the developed protocol.