Bi(OTf)₃-Catalyzed Multicomponent α-Amidoalkylation Reactions

Abstract

A bismuth(III) triflate catalyzed three-component synthesis of α-substituted amides starting from amides, aldehydes, and (hetero)arenes is reported. The reaction has a broad substrate scope, encompassing formaldehyde as well as aryl and alkyl aldehydes. Low catalyst loadings are required, and water is formed as the only side product. The scope and limitation of this method will be discussed.

Bismuth(III) triflate: An Efficient Catalyst for the Synthesis of Diverse Biologically Relevant Heterocycles

“…Therefore such beneficial features as a whole motivated the organic chemists to explore the catalytic applicability of bismuth(III) triflate in more heights and as a results, in the recent past, there were immense applications of bismuth(III) triflate as catalyst for the diverse organic synthesis . The catalytic applicability of this mild catalyst is well documented in the literature especially in various name reactions that include aldol reactions, Michael‐type reactions, Ene reaction, Diels Alder reaction, Friedel‐Crafts reaction,, Fries rearrangement, Beckmann rearrangements, Claisen rearrangement, Mannich reaction,, Prins reaction, Baeyer‐Villiger oxidation, and many more . The present review summarizes the recent developments of Bi(OTf) 3 catalyzed synthesis of biologically relevant heterocycles and when possible to compare its efficiency with that of the other metal triflates reported so far.…”

Cyclisations Catalysed by Bismuth(III) Triflate

“…As a Lewis acid catalyst, Bi(OTf) 3 presents activity borderline between that of the more oxophilic catalysts such as Al(OTf) 3 or Mg(OTf) 2 and that of the more carbophilic ones, such as (L)AuOTf . Examples of Bi(OTf) 3 activation of C–C double and triple bonds are available, as well as examples in which ketones and other oxygen‐containing substrates are selectively coordinated to Bi III . Functional‐group activation by Bi(OTf) 3 generally leads to the formation of carbocationic‐type intermediates, which further evolve in the presence of an endogenous or exogenous nucleophile.…”

1-(N-Acylamino)alkyltriarylphosphonium Salts with Weakened Cα-P+ Bond Strength—Synthetic Applications

“…The presence of a positively charged nucleofugal phosphonium moiety in the close surroundings of the N -acyl group determines its unique chemical properties such as high reactivity in α-amidoalkylations [1,2,3,4,5,6,7,8,9,10]. This type of reactions has enjoyed unflagging interest for years as a synthetic method with great potential, especially valuable for C-C and C-heteroatom bond formation [1,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37]. …”

“…Of course, the reactivity of N -acyliminium cation 2 or N -acylimine 3 toward a nucleophile is also significant [1,2,3]. To produce the proper α-amidoalkylating agents, for instance N -acyliminium cation 2 or N -acylimine 3 from the most popular precursors such as α-amido sulfones (Z = SO 2 Ar), N -(1-benzotriazolil)alkylamides (Z = Bt), and N -(1-alkoxyalkyl)amides (Z = OR), it is necessary to use catalysts, mainly Lewis acids (route a , Scheme 1 (I)) [18,19,20,21,22,23,24,25,29,30,31,32,33,34,35,36,37]. In contrast, 1-( N -acylamino)alkyltriphenylphosphonium salts 1 (Z = Ph 3 P + X − ) do not require the use of acidic catalysts because of the permanent positive charge on the phosphonium group.…”