Catalytic One‐Pot Synthesis of Cyclic Amidines by Virtue of Tandem Reactions Involving Intramolecular Hydroamination under Mild Conditions.

Abstract

Cycloamidines are prepared by combining an intramolecular hydroamination with a 1,3-dipolar cycloaddition of azides to the enamine double bond formed in the first step. In the case of enamines with an exo-methylene moiety, spiro triazolines are formed which rearrange to cycloamidines of type (IV) upon release of diazomethane. Enamines with an endo double bond furnish fused triazolines which release dinitrogen upon migration of a methyl group yielding cycloamidines of type (III). -(CHANG*, S.; LEE, M.; JUNG, D. Y.; YOO, E. J.; CHO, S. H.; HAN, S. K.; J.

Syntheses of N-sulfonyl-N,N-disubstituted amidines via a three-component free-radical coupling reaction of tertiary amines and arenesulfonyl azides with terminal alkynes

“…According to Chang [16][17][18][19][20][21][22][23][24][25][26][27] and Wang [28][29][30][31][32][33], arenesulfonyl azide 1 can react with the alkyne 2 to form the ketenimine species B in the There are possibly two competitive reaction routes for the formation of compound 4 (Scheme 4): the reaction between the intermediate B and hydrogen radical and the one between B and the free radical D. Therefore, a quantum chemical calculation has been performed. With DFT method implemented in Gaussian 09 package [48] under B3LYP/6-31+g** level, the reactants, products, possible intermediates and transition state geometries along the proposed reaction routes are optimized, and the reaction potential energy profiles are plotted in Figure 2.…”

“…Among various MCRs recently developed [2][3][4][5], the CuIcatalyzed MCRs of sulfonyl azides and alkynes with a third component, like amines, water, alcohol, imines, salicylaldehyde, aziridine or nitroolefin have attracted increasing research interests lately [6][7][8][9][10][11][12][13][14][15]. For example, Chang's [16][17][18][19][20][21][22][23][24][25][26][27] and Wang's [28][29][30][31][32][33] groups have applied these CuI-catalyzed MCRs on terminal alkynes respectively for the efficient generation of N-sulfonylamidines, amides, Nsulfonylazetidin-2-imines, iminocoumarins, 5-arylidene-2-imino-3-pyrrolines, and γ-nitro imidates. Our group has also applied this reaction for the efficient generation of benzoxazoline-amidines and 4-arylsulfonylimino-4,5-dihydrofurans by reacting sulfonyl azides and alkynes with Schiff bases or -ketoesters [34,35].…”

Amidines in Organic Synthesis

“…o-Alkynylamines can be used as a combined component of alkyne and amine, in which two kinds of cyclic amidines are formed dependent upon the conditions used [35] ( Table 3.2). When 5-amino-1-pentyne is reacted in the presence of copper catalyst, a five-membered amidine is obtained as a major product with the loss of one carbon (run 1).…”