Noncovalent interactions of squaramide derivatives were widely used in the field of supramolecular chemistry and molecular recognition [1-3]. Because of the remarkable hydrogen bond acceptor (O atoms) /donor (H atoms) character, the squaramide gains the aromaticity of the four-membered ring upon formation of hydrogen bonds either with the carbonyl oxygen atoms, the N-H groups, or both [4].
However, the turning point in squaramide chemistry occurred in 2008. Professor Viresh H. Rawal and his research group introduced hydrogen bond donor asymmetric organocatalysts wherein some of the H's of amide groups are replaced by chiral moieties (Fig 1) [5].
Fig. 1. General representation of chiral squaramide organocatalysts.
Since cinchona alkaloids have been explored in asymmetric synthesis for the last 35 years [6], modification of squaramides with cinchona motifs (07-7128; 07-7129; 07-8435; 07-8436) makes this bifunctional hydrogen-bonding catalyst even more useful for a wide range of asymmetric reactions. This includes mainly Michael addition, Sulfa-Michael addition, Mannich reaction, aza-Henry reaction, Strecker reaction as well as cascade or sequential reactions. In addition to the cinchona/squaramide catalysts, Strem offers other chiral squaramide-organocatalysts for asymmetric reactions (07-8510; 07-8511; 07-5610; 07-5611; 07-1025).
Squaramide Organocatalysts offered by Strem:
References:
Products Mentioned:
07-7128: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1S,2S)-2-(dimethylamino)cyclohexyl]amino]-3
cyclobutene-1,2-dione, 95%, (99% ee) (CAS# 1263205-96-4)
07-7129: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1R,2R)-2-(dimethylamino)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1211565-07-9)
07-8435: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(9R)-6'-methoxycinchonan-9-yl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1256245-79-0)
07-8436: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(8α,9S)-6'-methoxycinchonan-9-yl]amino]-3-cyclobutene-1,2-dione, 95%, (99% ee) (CAS# 1256245-84-7)
07-8510: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1R,2R)-2-(dipentylamino)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1411983-40-8)
07-8511: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1S,2S)-2-(dipentylamino)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1411983-41-9)
07-5610: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1R,2R)-2-(1-piperidinyl)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98% (CAS# 1211565-11-5)
07-5611: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1S,2S)-2-(1-pyrrolidinyl)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1346683-42-8)
07-1025: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1R,2R)-2-(dimethylamino)-1,2-diphenylethyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee) (CAS# 1223105-89-2)
Related Products:
07-1422: 3-[[(9R)-6'-Methoxycinchonan-9-yl]amino]-4-[[4-(trifluoromethyl)phenyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% de)(CAS# 1256245-80-3)
07-1423: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(1S,2S)-2-(1-piperidinyl)cyclohexyl]amino]-3-cyclobutene-1,2-dione, 98%, (99% ee)(CAS# 1312991-15-3)
07-1424: 3-[(2,6-Bis(dibromophenyl)amino]-4-[[(8α,9S)-6'-methoxycinchonan-9-yl]amino]-3-cyclobutene-1,2-dione, 95%
07-1426: 3-[(1R,2R)-2-Aminocyclohexylamino]-4-[3,5-bis(trifluoromethyl)phenylamino]cyclobut-3-ene-1,2-dione, 98%
07-1427: 3-[[3,5-Bis(trifluoromethyl)phenyl]amino]-4-[[(2S)-2-pyrrolidinylmethyl]amino]-3-cyclobutene-1,2-dione, 98% (CAS# 1356935-80-2)
High Purity Chiral Reagents
Organocatalyst