Cascade reactions of glycine Schiff bases and chiral phase transfer catalysts in the synthesis of α-amino acids 3-substituted phthalides or isoindolinones

Isoindolinones as Michael Donors under Phase Transfer Catalysis: Enantioselective Synthesis of Phthalimidines Containing a Tetrasubstituted Carbon Stereocenter

“…Nicely enough, the expected Michael adduct 6a was obtained in high yield and with higher enantioselectivity (56% ee) than when quinine and 7 were used and in a shorter reaction time (compare Entry 1 of Table 2 with the data of Table 1). Considering the promising results obtained under asymmetric phase transfer conditions, we tested other readily available chiral ammonium salts, widely used in asymmetric reactions [33,34,35,36,37,38,39]. The O -allyl ether derivative 8b was less effective in terms of yield and enantioselectivity, emphasizing the importance of maintaining free the -OH group at the C-9 position of the catalyst (Entry 2).…”

Synthesis of novel 4-acyl-2-amino-6-sulfanylpyridine-3,5-dicarbonitriles

“…For example, the cascade cyclization reaction of glycine Schiff bases with 2-cyanobenzaldehyde leads to phthalide or isoindolinone derivatives. 21 An efficient one-step synthesis of novel 4-acyl-2-amino-3,5-dicarbonitrile-6-sulfanylpyridines has been developed via the reaction of 2-acyl-1,1,3,3-tetracyanopropenides with thiols in DMSO containing dimsyl sodium. 2-Amino-3,5-dicarbonitrile-6-sulfanylpyridines are the subject of considerable interest due to their wide range of pharmaceutical, biological and medicinal applications and currently serve as a "privileged scaffold" due to their potential therapeutic applications.…”

Synthesis and Organocatalytic Asymmetric Nitro-aldol Initiated Cascade Reactions of 2-Acylbenzonitriles Leading to 3,3-Disubstituted Isoindolinones

“…A feature of this sequence of reactions relies on the selectivity of the Wittig reaction of the readily available 2-cyanobenzaldehyde 5 (Scheme 1), in which the cyano group in the 2 position is left non-reacted, while 2-cyanobenzaldehyde is reported to give efficient cascade reactions involving both the aldehyde and the cyano group. This leads to valuable 3-monosubstituted isoindolinones in the presence of a number of carbonand hetero-nucleophiles [21][22][23][24][25][26][27][28][29][30]. The cis/trans olefin mixture 6 was, then, hydrogenated under heterogeneous conditions and, taking advantage from our previous work [8], the obtained 2-alkylbenzonitriles 4 were selectively oxidized at the benzylic position with NBS/AIBN/H 2 O to afford the desired ketones 3 in good yields (Scheme 1).…”