RESUMO
The first diastereoselective synthesis of (-)-1-epi-lentiginosine from a common chiral trans-epoxyamide derived from 2-pyridincarbaldehyde is reported. This methodology involves a sequential oxirane ring opening and intramolecular 5-exo-tet cyclization of tosylate trans-epoxyalcohol to afford a diastereomeric mixture of indolizinium salts in a one-pot fashion, followed by regio- and diastereospecific pyridinium ring reduction.
RESUMO
A simple and efficient one-pot, three-component synthetic method for the preparation of coumarin-3-carboxamides was carried out by the reaction of salicylaldehyde, aliphatic primary/secondary amines, and diethylmalonate. The protocol employs piperidine-iodine as a dual system catalyst and ethanol, a green solvent. The main advantages of this approach are that it is a metal-free and clean reaction, has low catalyst loading, and requires no tedious workup.
Assuntos
Iodo , Aminas , Catálise , Cumarínicos , Iodetos , PiperidinasRESUMO
The synthesis of new chiral highly functionalized zwitterionic bicyclic lactams starting from acyclic ß-enaminoesters derived from (R)-(-)-2-phenylglycinol is described. The key step involved an intramolecular non-classical Corey-Chaykovsky ring-closing reaction of the corresponding sulfonium salts derived from ß-enaminoesters. This methodology permits the generation of two or three new stereogenic centers with high diastereoselectivity. The utility of these intermediates was demonstrated by the stereocontrolled total synthesis of cis-4-hydroxy-2-methyl piperidine and its corresponding pipecolic acid derivative.
RESUMO
In the title compound, C(21)H(26)N(2)O(3), the morpholine ring has a chair conformation and the dihedral angle between the two phenyl rings is 59.0â (3)°. The crystal packing is stabilized by inter-molecular O-Hâ¯O hydrogen bonds, generating a ribbon structure along the a axis. An intra-molecular N-Hâ¯O contact is also present.