Showing papers by "Shamsher S. Bari published in 2016"
TL;DR: In this article, a mild approach for the synthesis of halogenated 4-pyrazolylspirocyclic-β-lactams via halogen mediated intrasulfenyl cyclisation of cis -3-(prop-2′-ynyloxy)-4-pyraxolyl-β -lactam is described.
20 citations
TL;DR: 3-Allyl-3-phenylseleno-β-lactams acts as an efficient substrate for in situ oxidation and elimination in one step and is simple, convenient, fast, and very efficient.
16 citations
TL;DR: In this article, an effective and stereoselective synthesis of 3-(1′-methyl/phenylallyl)-3-phenylthio-β-lactams (3/4) using substituted allylsilane and Lewis acid is described.
Abstract: An effective and stereoselective synthesis of 3-(1′-methyl/phenylallyl)-3-phenylthio-β-lactams (3/4) using substituted allylsilane and Lewis acid is described. The reaction leads to the formation of a mixture of C-3 substituted allyl β-Lactams. However, these compounds on desulphurisation using tri-n-butyltinhydride and Raney Ni provide two separable diastereomers of the reduced product.
2 citations
TL;DR: A mild approach for the synthesis of halogenated 4-pyrazolylspirocyclic-β-lactams via halogen (I 2, Br 2, ICl) mediated intrasulfenyl cyclisation of cis -3-(prop-2′-ynyloxy)-4-pyraxolyl-β -lactam is described in this paper.
Abstract: A mild approach for the synthesis of halogenated 4-pyrazolylspirocyclic-β-lactams via halogen (I 2 , Br 2 , ICl) mediated intrasulfenyl cyclisation of cis -3-(prop-2′-ynyloxy)-4-pyrazolyl-β-lactams is described. The behaviour of the substrate towards the nature and variable amount of halogen was investigated. The structural and stereochemical analysis of novel β-lactams were carried out using FT-IR, NMR ( 1 H and 13 C), 2D-NMR (COSY and HSQC), elemental analysis (CHNS), mass spectrometry (EIMS) and single crystal X-ray crystallographic studies ( 3a , 6a , 7a ). NMR experiments were also performed on cis -3-chloro-4-pyrazolyl-β-lactams to establish the relationship between isomeric ratio of rotamers and nature of solvents. The cis or trans configuration of the hydrogen/chloro/nucleophile substituent at C-3 was assigned with respect to C4-H.