An N‐Linked Bidentate Phosphoramidite Ligand (N‐Me‐BIPAM) for Rhodium‐Catalyzed Asymmetric Addition of Arylboronic Acids to N‐Sulfonylarylaldimines

Abstract

A chiral N-linked C 2 -symmetric bidentate phosphoramidite (N-Me-BIPAM) was newly developed for the rhodium-catalyzed enantioselective addition of arylboronic acids to N-sulfonylimines. This ligand achieved high enantioselectivities in a range of 84-99% ee in additions of arylboronic acids to Ntosyl-and N-nosylarylaldimines.

Me‐bipam for Enantioselective Ruthenium(II)‐Catalyzed Arylation of Aldehydes with Arylboronic Acids

“…[11] However, the protocol is limited mainly becasue of the inefficiency of traditional bis(phosphine)s designed on the basis of C 2 symmetry. [13] We have developed new bidentate chiral phosphoramidites (Me-bipam, N-Me-bipam), derived from linked binol (binol = 1,1'-binaphthalene-2,2'-diol) units, for the enantioselective 1,4-addition of arylboronic acids to enones, [14] arylation of aldimines, [15] and hydrogenation of a-dehydroamino esters. [13] We have developed new bidentate chiral phosphoramidites (Me-bipam, N-Me-bipam), derived from linked binol (binol = 1,1'-binaphthalene-2,2'-diol) units, for the enantioselective 1,4-addition of arylboronic acids to enones, [14] arylation of aldimines, [15] and hydrogenation of a-dehydroamino esters.…”

Enantioselective Synthesis of Arylglycine Derivatives by Asymmetric Addition of Arylboronic Acids to Imines

“…The Rh(acac)(C 2 H 4 ) 2 previously used for addition of arylboronic acids to N-tosylaldimines resulted in lower selectivities (75% ee, entry 1). [30] The reaction took place smoothly in DME at 50 °C for 16 hours in the presence of Rh(acac)((R, R)-N-Me-bipam) with 97% yield and 96% ee (entry 2). Results of the arylation of N-tosyl-2-furylimine with representative arylboronic acids at 50 °C in DME are summarized in Table 1.…”

“…DME (2.0 mL) was added to the flask and the mixture was then stirred at 50 °C for 16 h, at which time the crude reaction mixture extracted using ethyl acetate, washed with saturated NH 4 Cl and brine, and dried over MgSO 4 . Chromatography of the crude reaction mixture on silica gel gave (S)-N-(2-(furanyl)(phenyl)methyl)-4-methylbenzenesulfonamide (5a) [14,16,18,19,30] …”

Rhodium‐Catalyzed Enantioselective Arylation of Aliphatic Imines

“…We have already reported enantioselective arylation of N ‐sulfonyl aromatic aldimines and iminoesters with aryl boron reagents in the presence of a rhodium/bis(phosphoramidite) ( N ‐Me‐BIPAM) catalyst. Herein, we report rhodium/ N ‐Me‐BIPAM‐catalyzed arylation of aliphatic imines with arylboronic acids, which proceeds enantioselectively to give a variety of optically active α‐branched amines.…”