Organocatalytic Carbon–Sulfur Bond-Forming Reactions

Cinchona Alkaloid Catalyzed Sulfa-Michael Addition Reactions Leading to Enantiopure β-Functionalized Cysteines

“…Again the best diastereoselectivity was obtained with the bulky Ph 2 CHSH thiol, that is 90:10 (entry 15) and also the ee of the major isomer was very high, 98%. With the ethyl-substituted α,β-unsaturated α-amino acid 24 the same trend in stereoselectivity was observed as with the tyrosine derivative 23 (entries [16][17][18], in particular, Ph 2 CHSH gave the best dr (93:7) and an excellent ee (98%) for the major diastereomer. With the purpose of converting the products of the SMA reactions into derivatives suitable for peptide chemistry we developed the procedure shown in Scheme 6.…”

“…Relatively few studies have been concerned with Cinchona alkaloid derivatives with a hydrogen bonding group located at one of the sites of the quinoline moiety. Recently, Palacio and Connon reported that Cinchona alkaloids with a urea moiety at the C5′ position are efficient catalysts for asymmetric sulfa-Michael addition (SMA) 17 to nitro-styrenes. 18 Previously we showed that a C6' thiourea derivative of quinidine is a highly efficient catalysts for the Henry reaction 2 and later Deng and co-workers reported that a C6' thiourea with a C9-methylanthracyl ether group is well suited as a catalyst for SMA reactions with α,β-unsaturated N-acetylated oxazolidin-2-ones (Scheme 1).…”

Organocatalysts for enantioselective synthesis of fine chemicals: definitions, trends and developments

“…Organocatalysis refers to the use of small organic molecules to catalyse organic transformations. During the last decades, organocatalysis has been included among the most important and successful concepts in asymmetric catalysis and it has been used for the enantioselective construction of C-C, C-N, C-O, C-S, C-P and C-halide bonds [15][16][17][18][19][20]. Furthermore, this new branch experienced a boom in the first eight years from its advent.…”

C3-Symmetric cinchonine-squaramide as a recyclable efficient organocatalyst for tandem Michael addition–cyclisation of malononitrile and nitrovinylphenols

“…[1][2][3][4][5][6][7] Among them, squaramide derived organocatalysts were applied in various asymmetric transformations. A series of enantiomerically pure compounds, such as indoles, tetrahydroxanthones, chromenes, quinazoline, naphthoquinones and substituted amino acid derivatives, which are widely distributed in pharmaceutical compounds and complex natural products, have been synthesized in recent years.…”