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1.
An indium-induced reduction-rearrangement reaction of nitro-substituted β-lactams has been used for facile synthesis of oxazines in aqueous ethanol. 相似文献
2.
[2+2] Carbonylative cycloaddition of chiral imines to various allyl halides, under CO pressure, in the presence of Et3N, a catalytic amount of Pd(OAc)2 and PPh3 as ligand, are carried out. Separable diastereomeric mixtures of chiral alkenyl-β-lactams are isolated with good yields and high trans diastereoselections. Absolute configurations are assigned by X-ray measurements and 1H NMR spectroscopy. 相似文献
3.
Using ring closing metathesis (RCM) as the key operation, a rapid access to β-lactams fused to a sultam moiety of variable ring size was developed from low cost, commercially available starting materials. An efficient RCM of 4-vinyl-azetidin-2-ones to give 1-aza-bicyclo[4.2.0]oct-4-en-8-ones is also reported. 相似文献
4.
The chemoselective and stereoselective synthesis of gem-difluoro-β-aminoesters or gem-difluoro-β-lactams was investigated from ethylbromodifluoroacetate and imines during Reformatsky reaction. Influence of various reaction parameters, such as nature of the amine part, nature of the chiral auxiliary, was evaluated. High levels of stereoselectivity (up to 98%) were obtained for gem-difluoro-β-aminoesters and gem-difluoro-β-lactams using either (R)-phenylglycinol or (R)-methoxyphenylglycinol. 相似文献
5.
Akio Kamimura Rie MoritaKenji Matsuura Hiromasa MitsuderaMasashi Shirai 《Tetrahedron》2003,59(50):9931-9938
A convenient stereoselective synthesis of β-lactams from thio-Michael/aldol tandem adduct is described. syn-Selective tandem reaction followed by amidation and intramolecular SN2 reaction provided β-lactams in diastereomerically pure form. The tandem reaction with aliphatic aldehydes, on the other hand, afforded a mixture of diastereomers of corresponding tandem adducts in about 3:1 ratio so that the conversion to β-lactams afforded a diastereomeric mixture. As an alternative approach to prepare the tandem adducts, the stereoselective Michael addition of aliphatic thiols to Baylis-Hillman adduct was developed. The stereoselectivity was sensitive to the protective group at the hydroxyl group and TBS protection brought the most successful syn-selective formation of the tandem adducts. The procedure could be applied to the ketone derivatives of the Baylis-Hillman adduct but no selectivity was observed for the nitrile-Baylis-Hillman adducts. A similar conversion of the adduct provided desired β-lactams stereoselectively. 相似文献
6.
Andrea Guerrini Greta Varchi Rizzo Daniele Cristian Samorì Arturo Battaglia 《Tetrahedron》2007,63(33):7949-7969
Reactions of chiral (2S)-enolates of dioxolan-4-ones, derived from lactic, mandelic, and phenyllactic acids, with aliphatic (SS)- and (SR)-tert-butylsulfinyl aldimines afforded conformationally restrained C2-disubstituted N,O-orthogonally protected 3-amino-2-hydroxyalkanoates in the form of N-sulfinyl protected 1′-aminodioxolan-4-ones. The product distribution showed that there is significant kinetic selectivity, due to the presence of ‘matched’ and ‘mismatched’ components, between the (S)- or (R)-tert-butylsulfinyl aldimines and the (2S)-enolates of the 1,3-dioxolan-4-ones. Selective methoxide-induced removal of the acetal group of the N-sulfinyl-1′-aminodioxolanones yielded the corresponding N-sulfinyl protected methyl alkanoates. In addition, the selective acid-induced removal of the sulfinyl group of the N-sulfinyl-1′-aminodioxolanones provided the corresponding N-unprotected 1′-aminodioxolanones, whose base-induced cyclization afforded the corresponding β-lactams. 相似文献
7.
Abstract Novel moni-β-lactams derived from esters of amino acids have been prepared in one step by the high pressure promoted [2 + 2] cycloaddition of enol ethers with isocyanates derived from esters of amino acids. The effect of substituents in the enol ether and in the isocyanate on the scope of the synthesis has been demonstrated. 相似文献
8.
A. Jarrahpour M. Motamedifar M. Zarei M. H. Youssoufi M. Mimouni Z. H. Chohan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):491-497
We report in this article the design and calculated molecular properties of 18 new mono-cyclic β-lactams 4–21, on the basis of one hypothetical antibacterial pharmacophore structure designed to interact with both of Gram-positive bacteria and Gram-negative bacteria. The in vitro biological evaluation of these compounds allowed us to point out new potential non-nucleoside hits, with MIC values in the range of 2–8 μg/mL active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. A correlation structure/antibacterial activities relationship of these monocyclic β-lactams is described. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
9.
Robert Łysek Ewa Woźny Marek Chmielewski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):327-340
Chiral formates derived from propane-1,2-diol, 1,2- O -isopropylidene- f - D -xylo- and f - D -gluco-furanoses were subjected to treatment with cyclopentadienyl [tris(trimethylsilylmethyl)] titanium (IV). A mixture of the corresponding ( E )- and ( Z )- g -silylvinyl ethers were obtained with predominance of the former. It was found that in contrast to ( Z )-vinyl ethers, which give g -lactams with chlorosulfonyl isocyanate, the ( E )-vinyl ethers gave unstable cycloadducts which undergo rapid elimination reaction leading to ( E )- f , g -unsaturated amides. 相似文献
10.
Bianca Flavia Bonini Luca Bernardi Mauro Comes-Franchini Gabriella Dessole Mariafrancesca Fochi Alfredo Ricci 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1273-1277
Abstract Enantiomerically pure 2-hydroxyalkyl, 2-aminoalkyl and 2-iminoalkyl ferrocenyl p-tolylsulfides are easily prepared in good yields and with complete diastereocontrol from (S)-(2-p-tolylthio)ferrocencarboxyaldehyde. 2-Iminoalkyl ferrocenyl derivatives can be used as ligands in asymmetric catalysis and as starting materials for asymmetric Staudinger reaction. 相似文献