107300-16-3Relevant academic research and scientific papers
Organocerium additions to proline-derived hydrazones: Synthesis of enantiomerically enriched amines
Denmark, Scott E.,Edwards, James P.,Weber, Theodor,Piotrowski, David W.
experimental part, p. 1278 - 1302 (2010/11/02)
The addition of organocerium reagents (from both organolithium and organomagnesium precursors) to chiral aldehyde hydrazones prepared from 1-aminoproline derivatives has been studied. The additions proceed in good yield and high diastereoselectivity and with good nucleophile (Me, n-Bu, i-Pr, t-Bu, Ph, etc.) and substrate scope (alkyl, alkenyl and aryl). The resulting hydrazines can be converted to amines by N-N bond cleavage through hydrogenolysis (Raney nickel) or by acylation and cleavage with Li/NH 3. The influence of the side chain on the diastereoselectivity was investigated through variation of the substituents to include more coordinating atoms (oxygen and nitrogen) as well as the removal of coordinating atoms. The SAMEMP auxiliary bearing a 2-methoxyethoxymethyl group gave the highest diastereoselectivities. Remarkably, auxiliaries bearing simple methyl and isobutyl substituents gave high selectivities as well. Hypotheses for the origin of the selectivity are presented.
Asymmetric synthesis of 6-alkyl- And 6-arylpiperidin-2-ones. Enantioselective synthesis of (S)-(+)-coniine
Lebrun, Stephane,Couture, Axel,Deniau, Eric,Grandclaudon, Pierre
, p. 2473 - 2476 (2008/02/05)
A variety of diolefinic hydrazides (1) have been assembled in a highly diastereoselective manner by addition of allyllithium to chiral SAMP hydrazones followed by N-acylation with acryloyl chloride. Substrates 1 undergo ring-closing metathesis to give the cyclic enehydrazides (5) which can be easily converted into virtually enantlopure 6-alkyl- or 6-arylpiperidin-2-ones (7). The versatility of this hydrazone addition-RCM protocol has been further exemplified by the conversion of the unsaturated heterocycle 5b into the piperidine alkaloid (S)-(+)-coniine.
Asymmetric synthesis of 3-aryl-substituted 2,3-dihydro-1H-isoindol-1-ones
Enders, Dieter,Braig, Volker,Raabe, Gerhard
, p. 1528 - 1535 (2007/10/03)
The first asymmetric synthesis of 3-aryl substituted 2,3-dihydro-1H-isoindol-1-ones via a tandem nucleophilic 1,2-addition ring closure procedure from SAMP and (or) RAMP hydrazones and subsequent oxidative cleavage of the auxiliary is reported.
Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 1: Synthesis and transformation of α-allenyl hydrazines
Breuil-Desvergnes, Valérie,Goré, Jacques
, p. 1939 - 1950 (2007/10/03)
The lithio-derivative of methoxyallene reacts with aldehyde hydrazones leading to expected α-allenyl hydrazines when ether is the solvent of the reaction. The yields are good as well as the diastereoselectivity observed in the case of SAMP-hydrazones. These hydrazines are cleanly transformed to N-dialkylamino-3-methoxy-3-pyrrolines when they are reacted with n-BuLi in THF. These compounds are sometimes accompanied by the isomeric 4-methyl azetidines. The N-dialkylamino-3-methoxy-3-pyrrolines are transformed to 3-methoxy-3-pyrrolines by hydrogenolysis of the nitrogen-nitrogen bond, to 3-alkoxy-pyrroles by treatment with a peracid and to 3-amino-pyrroles by acidic migration of the dialkylamino group. In the case of SAMP-hydrazines, the obtained 3-methoxy-3-pyrrolines have a high enantiomeric purity. Lastly, attempts to prepare α-hydrazino-esters (and subsequently α-amino-esters) by ozonolysis of the allenyl moiety failed due to the formation of a methyl glyoxylate.
