Mannich reactions of glycine Schiff base

Phase-transfer-catalyzed direct Mannich reaction of glycine Schiff base 2 with a-imino ester 79 was achieved with high enantioselectivity by the utilization of N-spiro chiral quaternary ammonium bromide le as catalyst (Table 5.14) [42],... 

A phase-transfer-catalyzed direct Mannich reaction of glycinate Schiff base 5 with a-itnino ester 78 was achieved with high enantioselectivity by the use of N-spiro chiral quaternary ammonium bromide 9e as catalyst (Scheme 11.21) [62]. This method enabled the catalyhc asymmetric synthesis of differentiatly protected 3-aminoaspartate, a nitrogen analogue of dialkyl tartrate, the utility of which was demonstrated by the conversion of product (sy -79) into a precursor (80) of strep-tohdine lactam. 

In 2004, the gronp of Maruoka reported the direct asymmetric Mannich reaction of glycinate Schiff base 104 with a-imino ester 10a catalyzed by A-spiro-C -symmetric chiral quaternary ammoninm bromide 103 to provide the protected 3-aminoaspartate 105 in 88% yield (81 18 dr, 91% ee) [60]. The latter was afterwards converted into a precnrsor of the streptothricin antibiotics core structure (Scheme 5.43). 

Scheme 17.33 Mannich reaction of glycine Schiff base with an a-imino ester.

Zhang HL, Syed S, Barbas CFI. Highly enantio- and diaster-eoselective Mannich reactions of glycine Schiff bases with in situ generated A-Boc-imines catalyzed by a cinchona alkaloid thiourea. Org. Lett. 2010 12(4) 708-711. 

After a thorough screening of different TaDiAS for the Mannich reaction of glycine Schiff base 14 with Boc-protected imines 134 it was found beneficial... 

Chiral two-center phase-transfer catalyst 202 possessing 2,6-disubstituted cyclohexane spiroacetal catalyzes the syn-selective Mannich-type reaction of glycine Schiff base 186 with N-Boc-protected aromatic imines as weU as enoUzable aUcyl imines (201) in high yields with moderate to good enantioselectivities (Scheme 28.24) [103],... 

Barbas et al. described highly enantio- and diastereoselective organocatalytic Mannich reactions of the glycine-derived Schiff base 63 with in situ generated aromatic A -Boc-protected imines from 64 (Scheme 5.31) [42]. Several thiourea-... 

Optically active, a,p-diamino acid derivatives are key structures in medicinally important compounds. Direct synffiesis of these segments has been reported using a Mannich-type reaction of a glycine Schiff base with imines. Shibasaki and co-workers obtained 5y -a,p-diamino acid... 

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