A chemospecific intramolecular Buchner reaction of N‐benzyl‐2‐cyano‐2‐diazoacetamides catalyzed by inexpensive copper(II) acetylacetonate (acac) has been achieved to synthesize a variety of 9‐aza‐1‐cyanobicyclo[5.3.0]deca‐2,4,6‐trien‐10‐ones, 5,7‐bicyclic products. The methodology involves sole chemoselectivity, an inexpensive metal catalyst, broad substrate scope, and moderate to excellent yields.
A chemoselective intramolecular Buchner reaction employing iodonium ylides as safe carbene precursors has been developed. Iodonium ylides are generated in situ from N-benzyl-2-cyanoacetamides and PhI(OAc)2 in the presence of base and undergo intramolecular Buchner reaction under catalysis from Cu(OAc)2·H2O, affording fused cyclohepta-1,3,5-triene derivatives in up to 85% yield. The N,N-dibenzyl-2-cyanoacetamides with two different benzyl groups undergo intramolecular Buchner reaction on their electron-rich benzyl groups selectively. The reaction is not sensitive to air and moisture and uses a safe alternative version of the corresponding diazo starting materials. The overall transformation involving the carbene pathway has been verified.
An economical, practical, and green protocol with which to synthesize 3‐alkylideneoxindoles from α‐diazo‐β‐ketoanilides has been developed. The approach employs inexpensive Cu(NO3)2·3H2O as catalyst and environmentally friendly water as solvent, and achieves moderate to excellent yields. The method has good tolerance to a range of N‐alkyl and N‐aryl groups, including electron‐withdrawing and electron‐donating groups on the aromatic ring, ortho‐, meta‐, and para‐substituents, and β‐aliphatic and β‐aromatic keto groups. A plausible mechanism involving intramolecular aromatic metal carbene electrophilic addition as the key step is proposed.
N-Aryl-2-cyanodiazoacetamidesp roduce polycyclic difluoroboron 2-oxoindoline-3-carboxamide complexes (up to pentacyclic conjugative and fused systems) directly ande xpeditiously in the presence of boron trifluoride etherate.T he boront rifluoride serves as both ac atalyst and reactant in the tandem reaction. Thet andem reactioni ncludes the carbenea romatic C À Hi nsertion, hydrolysiso ft he cyano group into an amide group,a nd boronation of the two amide carbonyl groups.T he synthetic method features the advantages of wide substrate scope and excellent chemoselectivity. Scheme3.Rationalef or the BF 3 -catalyzed hydrolysis of 2cyano-N,N-diphenylacetamide (4a).Scheme 4. Proposed mechanism for the tandemr eaction. 1 HNMR (400 MHz, CDCl 3 ): d = 7.26-7.04 (m, 4H), 3.82 (s, 2H), 3.65 (s,2H), 2.74 (s,2H), 2.04-1.96 (m, 2H); 13 CNMR
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