1690-74-0Relevant academic research and scientific papers
1,4-Dihydropicolinic acid derivatives: Novel NADH analogues with an altered connectivity pattern
Gómez, Elena,Miguel, Miriam,Jiménez, Oscar,De La Rosa, Guillermo,Lavilla, Rodolfo
, p. 3513 - 3516 (2005)
Sodium dithionite reduction of α-substituted N-alkylpyridinium salts (derived from picolinic acid derivatives) afforded the corresponding 1,4-dihydropyridines with a new substitution pattern, in which the electron-withdrawing group is at the α-position. These compounds promote biomimetic reductions and are hence considered functional NADH analogues.
Alkylation of 2-Lithio-N-Methylpiperidines and -pyrrolidines: Scope, Limitations, and Stereochemistry
Gawley, Robert E.,Zhang, Qianhui
, p. 5763 - 5769 (2007/10/03)
The scope and limitations of the alkylation of racemic and nonracemic 2-lithipiperidines and -pyrrolidines, obtained by transmetalation of the corresponding stannanes, is reported.These organolithiums react with a variety of electrophiles to afford 2-substituted pyrrolidines and piperidines in excellent yield.With primary alkyl halides the reaction proceeds with net inversion of configuration at the metal-bearing carbon in the piperidines; in the pyrrolidines there is a mixture of inversion and retention, with the former predominating.With most carbonyl electrophiles (carbon dioxide, dimethyl carbonate, methyl chloroformate, pivaloyl chloride, benzaldehyde, and dialkyl ketones), retention is observed in both cases.Electrophiles such as benzophenone, benzyl bromide, and tert-butyl bromoacetate afford racemic coupling products.A mechanistic interpretation is presented.
Photolytic reactions of chromium aminocarbene complexes. Conversion of amides to α-amino acids
Hegedus, Louis S.,Schwindt, Mark A.,De Lombaert, Stéphane,Imwinkelried, Rene
, p. 2264 - 2273 (2007/10/02)
A variety of tertiary amides was converted to chromium aminocarbene complexes by reaction with Na2Cr(CO)5 and trimethylsilyl chloride. Photolysis of these carbene complexes in methanol or tert-butyl alcohol solvent produced α-amino esters in good to excellent yield. Aminocarbene complexes containing chiral oxazolidine groups were synthesized and photolyzed in alcohol to produce chiral α-amino esters in 50-93% de. Pentacarbonyl[(dibenzylamino)(methyl)carbene]chromium(0) was prepared in high yield by the N-benzylation of the corresponding monobenzyl amino complex. Base-assisted alkylation of the methyl group with a variety of halides followed by photolysis in methanol produced the alkylated alanine methyl ester in excellent overall yield. Other aminocarbene complexes underwent similar reactions. With chiral, optically active aminocarbene complexes, the alkylated alanine derivative was produced with high diastereoselectivity.
REGIOSPECIFIC FUNCTIONALISATION OF CARBON ATOMS α TO HETEROCYCLIC NITROGEN
Koskinen, Ari,Lounasmaa, Mauri
, p. 1627 - 1634 (2007/10/02)
Previously, methods have been devised to functionalise the two endocyclic C atoms α to the piperidine N.In the present study we show that a nitrile substituent can be introduced also to the exocyclic α-C, making the centre either nucleo- or electrophilic in subsequent transformations.NMR studies have been used to gain knowledge of the mechanistic aspects leading to the observed regiospecificity.The generality of the method, along with the ease of operation, high yields and regiospecificity, make it highly versatile for synthetic purposes.
