Palladium(II)‐Catalyzed One‐Pot Enantioselective Synthesis of Arylglycine Derivatives from Ethyl Glyoxylate, p‐Toluenesulfonyl Isocyanate and Arylboronic Acids

Abstract

A palladium(II)-catalyzed, one-pot enantioselective synthesis of arylglycine derivatives from ethyl glyoxylate, p-toluenesulfonyl isocyanate and arylboronic acids giving moderate to good yields and enantioselectivity has been developed. This reaction provides a convenient and efficient method for the synthesis of arylglycines.

Ni(II)-catalyzed asymmetric alkenylations of ketimines

“…The stereochemical outcome can be explained using the model shown in Fig. 4 , similar to that of Rh- and Pd-catalysis 30 – 36 , 50 – 57 . The substrate coordinates with nickel and the sulfonyl group lies on the opposite side of diphenyl substituents on the oxazoline ring.…”

“…1b ) 45 – 47 . The Pd-catalyzed addition of alkenylboron reagents to double bonds, including imines, has not been described 50 – 57 . This may be due to potential side-reactions, such as homocouplings, Heck reactions, and aza-Wacker-type reactions.…”

Surgical wisdom

“…Although it has been applied to conjugate addition reactions involving arylboron reagents,13 the palladium‐catalyzed addition of arylboronic acids to imines has become feasible only recently 14. Subsequently, several asymmetric approaches have been developed for aldimine substrates,14c–h and chiral bidentate N‐heterocyclic carbene palladium catalysts have shown excellent catalytic activity 14e. However, there are still no reports concerning the palladium‐catalyzed addition of arylboronic acids to ketimines (including the reaction producing racemic products), and this may be due to the less nucleophilic nature of the arylpalladium species compared with that of the arylrhodium species 15.…”

Diastereo‐ and Enantioselective Catalytic Tandem Michael Addition/Mannich Reaction: Access to Chiral Isoindolinones and Azetidines with Multiple Stereocenters

“…This exceptionally high reactivity may be attributed to the higher electrophilicity of the N-tosyl aldimine or the strong coordination of the copper ion to the N-tosyl aldimine through a 1,3binding mode of the nitrogen atom of the imine moiety and the oxygen atom of the sulfonyl group. [7] We then focused our attention on this type of imine as the electrophilic tapping reagent and examined several catalytic systems. We used chalcone 1 a, N-tosyl aldimine 2 a, and Et 2 Zn as the reactants, and the reaction was performed at À10 8C in toluene for 12 hours.…”

“…We used chalcone 1 a, N-tosyl aldimine 2 a, and Et 2 Zn as the reactants, and the reaction was performed at À10 8C in toluene for 12 hours. With L1 as a ligand, we screened a variety of copper sources including copper(I) and copper(II) species, and found the stereoselectivity was significantly affected by the nature of the counterion of the copper salts (Table 1, entries [1][2][3][4][5][6][7][8]. The more coordinating counterions proved to be more suitable, and among those tested, CuBr led to the best results with respect to reactivity and stereoselectivity ( To extend the application of the reaction, a variety of N-sulfonyl aldimines were subjected to the optimal reaction conditions using chalcone 1 a and Et 2 Zn.…”