Gold‐Catalyzed Asymmetric Intramolecular Cyclization of N‐Allenamides for the Synthesis of Chiral Tetrahydrocarbolines

Abstract

Highly enantioselective gold-catalyzed intramolecular cyclization of N-allenamides was implemented by utilizing ad esigned chiral sulfinamide phosphine ligand (PC-Phos). This represents the first example of highly enantioselective intramolecular cyclization of N-allenamides.T he practicality of this reaction was validated in the total synthesis of (R)desbromoarborescidine Aand formal synthesis of (R)-desbromoarborescidine Ca nd (R)-deplancheine.M oreover,t he catalyst system PC-Phos/AuNTf 2 proved to be specifically efficient to promote the desymmetrization of N-allenamides in excellent yields with satisfactory ee values.

Organocatalytic alkylation of carbohydrate‐containing aldehydes with dihydroquinoline N,O‐acetals: Absolute configuration of 1,2‐dihydroquinolines

“…Derivatives 5a and 5b were obtained in 57% and 66% yield, respectively. Compounds 4a and 4b are versatile reagents, which have been extensively employed for the design of biologically relevant compounds such as for instance lamellarin alkaloids, tetrahydrocarbolines, (−)‐crinipellin A, (+)‐swainsonine and (+)‐8‐episwainsonine, labystegines, and cycloalkane‐fused indoles . Final acid hydrolysis unmasked the carbonyl group, and compounds 1a and 1b have been isolated in a 40% and 64% yield, respectively, after filtration on silica gel (Scheme ).…”

Diastereoselective Three-Component 1,3-Dipolar Cycloaddition to Access Functionalized β-Tetrahydrocarboline- and Tetrahydroisoquinoline-Fused Spirooxindoles

“…Accordingly, the development of efficient synthesis strategies for preparing polycyclic indoles with potential biological activity is still highly desirable. Fortunately, 1,2,3,4-tetrahydro-9H-pyrido [3,4-b]indole (THPI) 2 [46][47][48] and 1,2,3,4-tetrahydroisoquinolines (THIQs) 5 [49,50] have been proven to be valuable synthons, while still undeveloped in the 1,3-dipolar cycloadditions. Here, we present a diastereoselective three-component 1,3-dipolar cycloaddition of isatins (1), THPI 2 (or THIQs 5), and (E)-3-(2-nitrovinyl)-indoles (3) under green conditions, allowing for rapid access to functionalized β-tetrahydrocarboline-and tetrahydroisoquinoline-fused spirooxindoles (4 and 6) in excellent yields and diastereoselectivities (Scheme 1b).…”

Chiral Ligands for Au(I), Au(III), and Au(I)/Au(III) Redox Catalysis

“…In 2017, J. Zhang and co‐workers utilized a structurally novel chiral sulfinamide monophosphine ligand to achieve intramolecular cyclisation of N‐allenamides 22 a for the efficient construction of enantioenriched fused tetrahydro‐1H‐ β ‐carboline derivatives 22 b in excellent yields with up to 97 % ee (Entry 22) [48] . The design of PC‐Phos ligand ( L22 ) is based on the merger of structural components from Ming‐Phos [39] and Xant‐Phos in order to broaden the space and change the angle between the phosphine and sulfinamide.…”