Organocatalytic Enantioselective Strecker Reaction with Seven‐Membered Cyclic Imines

Abstract

Scheme 6. Plausible transition-state model and X-ray crystal structure of 3 i. COMMUNICATIONS

Stereoselective Oxidative Mannich Reaction of Ketones with Dihydrodibenzo‐Oxazepines via a Merger of Photoredox‐/Electro‐Catalysis with Organocatalysis

“…Other amino acids (C-2 to C-4) were screened as organocatalysts along with NaOH as an additive; however, none provided better results than C-1 (entries [10][11][12]. A further variation on the loading of catalyst and additive revealed that C-1 (10 mol %) and NaOH (10 mol %) turned out to be the best condition for this transformation (entries [13][14][15]. The amount of acetone was further screened; [h,j] C-1 NaOH 3 4 93 95 17 [h,k] C-1 NaOH 3 4 75 95 18 [h,l] C-1 NaOH 12 -51 77…”

“…Due to attractive biological activities, some enantioselective syntheses of these compounds have been developed, which mainly rely on the nucleophilic addition to the dibenzoxazepines 4 (Scheme 1). [8] Using this strategy, asymmetric Mannich reaction, [9] alkylation, [10] ChemSusChem www.chemsuschem.org allylation, [11] domino Mannich/Michael reaction, [12] aza-Henry reaction, [13] Strecker reaction, [14] and hydrogenation reaction [15] have already been reported. Despite these efforts, the catalytic enantioselective access to dihydrodibenzo-oxazepine derivatives remained at the stage of infancy.…”

Catalytic Diastereo- and Enantioselective Synthesis of Tertiary Trifluoromethyl Carbinols through a Vinylogous Aldol Reaction of Alkylidenepyrazolones with Trifluoromethyl Ketones

“…Next, we evaluated the use of additives in order to increase the yield and the enantioselectivity of the reaction. When molecular sieves 5 Å or CF 3 CH 2 OH 19 were added to the reaction mixture, the alcohol 3aa was obtained with lower enantiomeric excess (69% ee, entries 7 and 8). While the use of 1 equiv of K 2 CO 3 afforded product 3aa as a racemic mixture, probably caused by a background reaction (entry 9).…”

Dibenzothiazepine Based MCR Chemistry

“…[2,3,21,22] Multicomponent reactions chemistry (MCRs) [23] is one of the tools that allows for fast and convergent access on polycyclic (more than three rings), diverse www.eurjoc.org and complex adducts. [24][25][26][27][28] In general, MCRs have been utilized towards the 1,5-dibenzothiazepine core, e. g. Ugi-Joullie threecomponent reaction (UJ-3CR), [29] Mannich, [30] Strecker, [31] Pudovik reaction [32] and aza-Henry. [33,34] However, there is only one report of an MCR-based annulation of this scaffold towards polycyclic and rigid derivatives.…”