(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers
نویسندگان
چکیده
Organocatalysis, now running its second decade of life, is being considered one of the main tools a synthetic chemist has to perform asymmetric catalysis. In this review the synthesis of six-membered rings, that contain multiple chiral centers, either by a ring closing process or by a functionalization reaction on an already existing six-membered ring, utilizing bifunctional (thio)ureas will be summarized. Initially, the use of primary amine-thioureas as organocatalysts for the above transformation is being discussed, followed by the examples employing secondary amine-thioureas. Finally, the use of tertiary amine-thioureas and miscellaneous examples are presented.
منابع مشابه
N-(2,2-Dimethylpropanoyl)-N′-(2-methoxyphenyl)thiourea
In the title compound, C(13)H(18)N(2)O(2)S, the carbonyl-thio-urea fragment is nearly planar with an r.m.s. deviation of 0.0096 Å. The dihedral angle between carbonyl-thio-urea group and the benzene ring is 19.16 (16)°. There are two intra-molecular N-H⋯O hydrogen bonds, which lead to two pseudo-six-membered rings. Weak intra-molecular C-H⋯S hydrogen bonding also occurs.
متن کاملReview High-performance liquid chromatographic enantioseparation of drugs containing multiple chiral centers on chiral stationary phases
In recent years there has been considerable interest in the synthesis and separation of enantiomers of organic compounds especially because of their importance in the biochemistry and pharmaceutical industry. High-performance liquid Chromatography is a very useful method for the direct separation of enantiomers. However, about 30−40 years ago, commercially available chiral stationary phases wer...
متن کامل3-Hydroxy-4-methoxybenzaldehyde thiosemicarbazone hemihydrate
The asymmetric unit of the title compound, C(9)H(11)N(3)O(2)S·0.5H(2)O, comprises two crystallograpically independent thio-semicarbazone mol-ecules (A and B) and a water mol-ecule of crystallization. In each of the thio-semicarbazone mol-ecules, intra-molecular O-H⋯O and N-H⋯N hydrogen bonds form five-membered rings, producing S(5) ring motifs. Inter-molecular O-H⋯S and N-H⋯O inter-actions betw...
متن کامل1-Methyl-3-phenylimidazolidine-2-thione
The asymmetric unit of the title cyclic thio-urea derivative, C10H12N2S, comprises two mol-ecules, each of which has a twist about the CH2-CH2 bond within the five-membered ring. The major difference between the independent mol-ecules is manifested in the relative orientations of the five- and six-membered rings [dihedral angles between the least-squares planes = 28.03 (11) and 41.54 (11)°]. A ...
متن کاملStereoselective and enantioselective synthesis of five-membered rings via conjugate additions of allylsulfone carbanions*
Abstract: This lecture describes some of our studies of lithio derivatives of allyl sulfone carbanions which add α-regioselectively as well as anti diastereoselectively to Michael acceptor olefins. This can be ascribed to chelation in the Michael addition step. When the reaction leads to subsequent ring closure by using a bromoallyl sulfone, the latter acts as a methylenemethane synthon in a (3...
متن کامل