Stereoselective synthesis of chiral β2,3-disubstituted-β-amino acid derivatives using Pd/In transmetallation cascade processes

Abstract

Abstract-A new, highly efficient synthesis of chiral β 2,3 -disubstituted-β-amino acid derivatives has been developed, based on an allylation procedure employing allene and a catalytic Pd/In bimetallic process

Copper‐Catalyzed Borylative Cross‐Coupling of Allenes and Imines: Selective Three‐Component Assembly of Branched Homoallyl Amines

“…Theu se of allenes and imines in catalytic three-component coupling reactions which involve the in situ generation of allyl metals has emerged as an exciting strategy to afford valuable,substituted homoallylic amines (Scheme 1b). [5][6][7] For example,t he groups of Oshima, [5e] Grigg, [5a-d] and Malinakova [5f-i] have studied the catalytic generation of allyl metals from allenes,byorganometallic addition, and their addition to imines.I na ni mportant advance,M orken and co-workers described the asymmetric palladium-catalyzed diboration of allenes with subsequent addition of an imine to trap the functionalized allyl borane intermediates in as eparate operation. [5j] In the study from Morken et al,linear adducts were obtained and products were typically isolated as ketones after in situ oxidation of the CÀBb ond.…”

“…In the above studies, expensive and supply-risk platinum-group metals were used. [5] Herein we describe ar egio-, chemo-, and diastereoselective copper-catalyzed three-component coupling of allenes, [8] bis(pinacolato)diboron, and imines, [9,10] proceeding via allyl coppers to give readily isolable,branched homoallylic amines bearing versatile amino,a lkenyl, and borane functionalities (Scheme 1c). Faced with the challenge of controlling the regioselectivity of borylcopper addition to allenes,itwas clear that the use of awell-defined, bench-stable,and commercially available precatalyst would be highly desirable.O ptimization of the process commenced with using 5mol %I PrCuCl, the allene 1a,6mol %o fK O tBu, and 1.1 equivalents of B 2 pin 2 in the borylative cross-coupling with the N-phenyl imine 2a.T he corresponding homoallylic amine 3a was obtained with 27 % conversion ( Table 1, entry 1).…”

Copper‐Catalyzed Borylative Cross‐Coupling of Allenes and Imines: Selective Three‐Component Assembly of Branched Homoallyl Amines

“…The use of allenes and imines in catalytic three‐component coupling reactions which involve the in situ generation of allyl metals has emerged as an exciting strategy to afford valuable, substituted homoallylic amines (Scheme b) . For example, the groups of Oshima, Grigg,– and Malinakova– have studied the catalytic generation of allyl metals from allenes, by organometallic addition, and their addition to imines. In an important advance, Morken and co‐workers described the asymmetric palladium‐catalyzed diboration of allenes with subsequent addition of an imine to trap the functionalized allyl borane intermediates in a separate operation .…”

Polycyclic Compounds from Allenes via Palladium-Mediated Intramolecular Carbopalladation/Nucleophilic Substitution Cascade Processes

“…An additional value of this methodology was created by the development of transmetalation processes, where the generated electrophilic allyl-palladium becomes a nucleophilic allyl metal species in situ, allowing a range of different transformations. [43][44][45][46][47] Strategically, there are several modifications of three-component reactions involving halide/pseudohalide, allene and nucleophile, depending on whether the carbometallation and nucleophilic displacement steps are performed inter-or intramolecularly (Scheme 2). All these approaches are reported in the litera-…”