Phosphine Catalyzed Enantioselective Cascade Reaction Initiated by Intermolecular Cross Rauhut‐Currier Reaction of Electron‐Deficientortho‐Formyl Styrenes

Abstract

The Rauhut‐Currier reaction generally employs α,β‐unsaturated carbonyl compounds and nitroalkenes as the substrates. Here we develop an enantioselective formal [4+2] annulation reaction, which is initiated by an intermolecular cross Rauhut‐Currier reaction between electron‐deficient ortho‐formyl‐styrenes and 2‐benzoyl‐acrylonitriles catalyzed by an L‐phenylglycine‐derived phosphine, followed by a cascade aldol/acyl transfer/elimination process. A series of enantioenriched dialin frameworks with an unusual exo‐double bond are furnished in fair to good yields with moderate to excellent enantioselectivity, and the architectures with higher molecular complexity can be constructed via simple transformations.

Solvent- and catalyst-dependent palladium-catalyzed switchable chemodivergent cascade cyclizations of trimethylenemethanes with ortho-formyl cinnamates

“…Fluoro-substituted ortho -formyl cinnamates exhibited overall lower reactivity, monofluoro-substituted ortho -formyl cinnamate was totally inactive (see the ESI†), and difluoro-substituted 1m delivered product 3m in 45% yield at a higher reaction temperature, indicating the importance of a strong electron-withdrawing group in the phenyl ring. 11 Furthermore, the practicality of this methodology has been verified by a scale-up synthesis of 3f on a 1.0 mmol scale although in a slightly reduced yield.…”

“…Yet, there was no improvement by employing benzoic acid C1 and BINOL-derived phosphonic acid C2 as HBD catalysts (entries 9 and 10). Surprisingly, an array of N-aryl substituted ureas and thioureas gave better results (entries [11][12][13][14][15][16], in which both the reactivity and yield were enhanced dramatically. Schreiner's urea C6 10 with a bis(3,5-trifluoromethyl) phenyl group proved to be the best HBD catalyst, giving 4a in 92% yield (entry 14).…”

Recent Developments in Intermolecular Cross‐Rauhut‐Currier Reactions

“…19 ) and begins with an intermolecular cross RC reaction between electron‐deficient o ‐formyl‐styrenes 81 and 2‐benzoylacrylonitriles 82 , followed by a cascade aldol/acy (Scheme 44). [32] Enantioenriched dialin frameworks with a unique exodouble bond are synthesised with moderate to excellent enantioselectivity (73–99 %) in fair to good yields (32–81 %).…”

Effects of Anchimeric Assistance in Phosphonium Enolates Chemistry

“…To date, the efficiency of chiral tertiary phosphines bearing a thiourea, mono-, or diamide has been largely demonstrated in asymmetric phosphine-catalyzed Morita-Baylis-Hillman [18][19][20][21][22][23][24], Rauhut-Currier [25][26][27][28][29], and Michael [30][31][32][33][34][35] reactions , cycloaddition [36][37][38][39][40], and other reactions; Scheme 5 shows the main structural types of such catalysts.…”