Rh‐Catalyzed Transannulation of Pyridotriazoles with Alkynes and Nitriles

Abstract

1, 2 oder 3 N‐Atome: Vielfältige Pyrrolo‐ und Imidazopyridine mit verbrückendem N‐Atom sind durch rhodiumkatalysierte Transanellierung aus Pyridotriazolen und Alkinen bzw. Nitrilen zugänglich (siehe Schema). Substituierte Pyridotriazole dienen auch als beständige Vorstufen für Rhodium‐Carbenoide, die ohne besondere Schutzvorkehrungen oder langsame Zugabe eines Reaktionspartners erhalten werden.

Chiral Guanidine/Copper Catalyzed Asymmetric Azide‐Alkyne Cycloaddition/[2+2] Cascade Reaction

“…[1] When azides containing astrong electron-withdrawing group at the N1 atom such as N-sulfonyl azides were used, the CuAACinitiated intermediates enabled further transformations. Additionally to serving as precursors to the diazoimine species and azavinyl metal carbenes, [2] the triazolyl copper intermediates I of N-sulfonyl azides undergo ring-opening rearrangement upon the release of nitrogen, allowing the formation of au nique ketenimine species II or alkynamide species III for diverse synthesis (Scheme 1a). [3] Pioneered by Fokin and Chang,c atalytic multi-component reactions [4] among sulfonyl azides,t erminal alkynes,a nd nucleophiles have been utilized to construct the amidines,a mides and other products by trapping these ketenimine species II (Path b).…”

Transition‐Metal‐Catalyzed Denitrogenative Transannulation: Converting Triazoles into Other Heterocyclic Systems

“…Recently, Gevorgyan and co-workers demonstrated [16] that the diazoform 2a,b may be used as a source of a rhodium carbenoid species (Scheme 2). Thus, it was shown that the 7-halo-substituted pyridotriazole 3b , in the presence of a rhodium catalyst, released dinitrogen from 2b to produce the corresponding rhodium carbenoid 4b .…”

“…[16] It was found that treatment of the pyridotriazole 3b with phenyl acetylene in the presence of Rh 2 (OAc) 4 , resulted in a mixture of the cyclopropene 6a and indolizine 7a , the products of the [2+1] and the formal [2+3] cycloaddition reactions, respectively. Interestingly, the cyclopropene 6a , under the employed reaction conditions, did not undergo cycloisomerization into indolizine 7a , thereby suggesting independent mechanistic paths for their formation.…”

Rhodium(II)‐Catalyzed Formal [4+1]‐Cycloaddition of Pyridotriazoles and Propargyl Alcohols: Synthesis of 2,5‐Dihydrofurans

“…[14] Notably, in these advances, the compatibility of the catalysts with corresponding substrates is essential in the development of selective catalytic transformations. [16][17][18][19][20] In most of these transformations, pyridotriazole served as a three-element "NÀCÀC" synthon in [3 + 2]-cycloaddition with alkynes (Scheme 1b), [16] alkenes, [18] nitriles, [19] amides. [15] In the last decade, Gevorgyan and others have reported a variety of cycloaddition reactions with pyridotriazole as a-pyridyl carbene precursor.…”