Gallium(III)-catalyzed tandem cycloisomerization/Friedel–Crafts alkylation: a facile synthesis of 2,5-disubstituted furans

A tandem cycloisomerization/Friedel–Crafts alkylation of indoles has been achieved in a one-pot process to produce 2,5-disubstituted furans using gallium-catalyzed sequential nucleophilic addition onto metal-activated 1-alkynyl-2,3-epoxy acetates. The reaction proceeds efficiently under mild conditions with complete regioselectivity to afford the substituted furan derivatives in good yields with high diversity.     

(S)-(−)-2-Methyl-2-Phenylsuccinic Anhydride,a Novel Resolving Reagent and its Application to Resolution of CIS-5-Amino-4-Phenyl-1,3-DIOXANE

Abstract

A new resolving reagent, (S)-(?)-2-methyl-2-phenylsuccinic anhydride (5) for the resolution of amines via covalent bond formation and its application to the resolution of aminodioxane (±)-(1) is described. The d.e. of the amides (7) and (8) has been determined by studying ¹H-NMR spectra.     

Regiospecific Functionalization of Cyclic Allenes with Catecholeorane

Reaction of diborane¹ and disiamylborane² with cyclic allenes, resulted in the formation of a mixture of products resulting from the addition of boron at the central carbon as well as terminal carbon. Fish has reported that addition of 4, 4, 6-trimethyl-1, 3, 2-dioxaborinane to 1, 3-disubstituted allenes takes place at the central carbon atom preferentially when the hydroboration was done at 130° for 35–50 h in a sealed tube.³ The reactivity and stability of catecholborane at high temperatures which is known to provide greater stearic     

Preferential Reactivity of Pyridylmagnesiumchloride with N,N-Dialkyl Arylamides over Carbonitriles: Synthesis of 2-(Aroyl) Pyridines

Reaction of 2-pyridylmagnesium chlorides with N,N-dialkyl arylamides afford exclusively 2-(aroyl) pyridines in high yields and purity without the formation of any tertiary alcohol. This method employs easily available raw materials and avoids the use of hazardous lithium reagents and cryogenic conditions. Further, preferential reactivity of this Grignard reagent with N,N-dialkyl arylamides over its carbonitrile counterparts offers a variety of 2-(aroyl) pyridines including the ones containing carbonitrile groups on the aryl ring.     

Iron(III) Chloride–Promoted Direct Conversion of Aryl/Alkyl Cyanides to Esters

Aryl/alkyl cyanides were quickly converted into the corresponding esters in the presence of iron(III) chloride in refluxing alcohols with very good yields.