187035-29-6Relevant academic research and scientific papers
Selective reduction of N-nitroso aza-aliphatic cyclic compounds to the corresponding N-amino products using zinc dust in CO2–H2O medium
Yang, Weiqing,Lu, Xiang,Zhou, Tingting,Cao, Yongjing,Zhang, Yuanyuan,Ma, Menglin
, p. 780 - 783 (2018/10/20)
[Figure not available: see fulltext.] A new method for reduction of N-nitroso aza-aliphatic cyclic compounds employing zinc in pressurized CO2–H2O medium has been developed. H2O and NH4Cl were used as hydrogen donors, and reduction was performed under environmentally benign conditions. The presented approach allowed to obtain the respective N-amino products selectively and in excellent yields (up to 97%).
Stereoselective alkylations of chiral nitro imine and nitro hydrazone dianions. Synthesis of enantiomerically enriched 3-substituted 1-nitrocyclohexenes
Denmark, Scott E.,Ares, Jeffrey J.
supporting information; scheme or table, p. 9647 - 9656 (2009/04/11)
(Chemical Equation Presented) Dianions of chiral nitro imines (generated by a combination of LDA and s-BuLi) underwent diastereoselective alkylation with methyl, butyl, isopropyl, allyl, and methallyl iodides. In contrast to the behavior of simple metalloenamines, the most selective auxiliary contained no coordinating groups but did possess a large steric difference between the two substituents. The yield and selectivity of the alkylations were improved by the addition of HMPA or DMPU. The use of (S)-1-naphthylethylamine as the auxiliary afforded the R absolute configuration of the alkylation products. This stereochemical outcome could be rationalized by simple steric approach controlled alkylation in a conformationally fixed, internally coordinated dianion. A SAMP nitro hydrazone gave poorer yields and selectivities.
ASYMMETRIC MICHAEL ADDITIONS VIA SAMP-/RAMP-HYDRAZONES ANTI-DIASTEREO- AND ENANTIOSELECTIVE SYNTHESIS OF 3,4-DISUBSTITUTED 5-OXO-ALKANOATES
Enders, Dieter,Papadopoulos, Kyriakos,Rendenbach, Beatrice E.M.,Appel, Rolf,Knoch, Falk
, p. 3491 - 3494 (2007/10/02)
An efficient and highly anti-diastereo-(de=90-100percent) and enantioselective (ee=92-100percent) synthesis of 3,4-disubstituted 5-oxo-alkanoates 3 in good overall chemical yields is described.The procedure involves the asymmetric Michael addition of aldehydes or ketones to enoates via their lithiated SAMP-/RAMP-hydrazones.Both enantiomers are accessible at will.
ASYMMETRIC SYNTHESES VIA METALATED CHIRAL HYDRAZONESOVERALL ENANTIOSELECTIVE α-ALKYLATION OF ACYCLIC KETONES
Enders, D.,Eichenauer, H.,Baus, U.,Schubert, H.,Kremer, K. A. M.
, p. 1345 - 1359 (2007/10/02)
A general method is described, which allows the overall enantioselective α-alkylation of acyclic ketones in good overall yields (44-86percent, 4 steps) and enantioselectivities ranging routinely from >94percent ee up to virtually complete asymmetric induction (99.5percent ee).The acyclic ketones are transformed to their corresponding "SAMP-hydrazones" (S)-2 by reaction with the enantiomerically pure hydrazine (S)-1-amino-2-methoxymethyl-pyrrolidine , readily available from (S)-proline.Metalation to form chiral azaenolates (S)-3 of ECCZCN-configuration and then alkylation to product hydrazones 4, followed by hydrazone cleavage via acidic hydrolysis of methiodides 9 in a two phase system or ozonolysis, leads to α-substituted, enantiomerically enriched, acyclic ketones 5.In special cases, where a phenyl group is directly attached to the newly generated center of chirality (5n,o,p), only low enantiomeric excesses are observed. 17 Examples, including first applications in natural product synthesis (cf 5a,b,e, and h) are summarized.
