Domino [4 + 1]-annulation of α,β-unsaturated δ-amino esters with Rh(ii)–carbenoids – a new approach towards multi-functionalized N-aryl pyrrolidines

Abstract

Catalytic decomposition of diazomalonates and other diazoesters using Rh(II)- and Cu(II)-complexes in the presence of α,β-unsaturated δ-(N-aryl)amino esters gives rise to the formation of multi-functionalized pyrrolidines with yields of up to 82%. The reaction apparently occurs as a domino process involving the initial N-ylide formation followed by intramolecular Michael addition to the conjugated system of amino esters to afford the pyrrolidine heterocycle. The whole process can also be classified as a [4 + 1]-annulation of the δ-amino α,β-unsaturated ester with the carbenoid intermediate.

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

“…At first, we studied reactions of thioamides 1 with diazomalonates 2a , b , which usually display high reactivity in Rh-catalyzed transformations [ 26 , 48 – 51 ] ( Table 1 ). Traditionally, similar catalytic reactions of diazomalonates occur under relatively mild conditions [ 26 ].…”

“…Similar intramolecular transformations of intermediate ylides with several nucleophilic reaction centers in the initial substrate, are also possible. The known examples of such reactions are for instance syntheses of multisubstituted indolines [ 23 – 25 ], pyrrolidines [ 26 – 29 ], dihydropyrroles [ 29 ], tetrahydrofurans [ 27 – 28 ], and 2,5-dihydrofurans [ 31 – 32 ], which proceed as intramolecular interaction of generated ammonium or oxonium ylides with carbonyl groups [ 23 , 27 – 28 ], C=C double [ 24 – 26 ], or C≡C triple [ 29 – 32 ] bonds in the structure of the initial molecule ( Scheme 1 ).…”

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II)-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

“…By this means during the course of Rh(II)-catalyzed reactions of aroyldiazomethanes 2a–c, diazoketoesters 3a,b and diazodiketone 3c with aminoester 1 , contrary to the similar reactions of diazoesters [15], two other reaction processes were observed – the Wolff rearrangement and the assumed oxidative cleavage of the initial reaction products.…”

“…Recently we have shown that the catalytic decomposition of diazomalonates and other diazoesters using Rh(II)- and Cu(II) - complexes in the presence of α,β-unsaturated δ-( N -aryl)amino esters 1 provides a good way for the synthesis of multi-functionalized N -arylpyrrolidines by the same “metal–carbene” methodology with yields of up to 82% [15]. The reactions occur as a domino process involving an initial formation of N -ylides A followed by the intramolecular Michael addition with the conjugated system of the amino ester to afford N -arylpyrrolidines B (Scheme 1).…”

Domino reactions of diazodicarbonyl compounds with α,β-unsaturated δ-amino esters: a convenient way towards 2-oxopiperidines, dihydropyridinones and isoquinolinediones

“…3 Of special interest are the domino reactions of diazo compounds with different amino substrates, since they provide a way for the preparation of a variety of useful nitrogenous heterocyclic compounds. 5 However, all attempts to extend the same methodology to diazo ketoesters and diazo diketones 2 and 3 were unsuccessful. 5 However, all attempts to extend the same methodology to diazo ketoesters and diazo diketones 2 and 3 were unsuccessful.…”