No abstract

A facile synthesis of novel monocyclic trans-and cis-3-oxy/thio/seleno-4-pyrazolyl-β-lactams (5, 6) is described. The reaction of 2-methoxy/phenoxy/benzyl/phenylthio/seleno ethanoic acids or acetoxyacetyl chloride 4 with pyrazolyl substituted Schiff′s bases 3a-d using POCl 3 and Et 3 N in refluxing toluene furnished β-lactams (5, 6). These synthesized β-lactams have been characterized by spectroscopic techniques viz. NMR ( 1 H, 13 C and 77 Se), FT-IR, mass spectrometry (EI-MS and HRMS) and elemental analysis. Single crystal X-ray crystallographic study of trans-1-(4′-methoxyphenyl)-3-methoxy-4-(5′-chloro-3′-methyl-1′-phenyl-1H-pyrazol-4′-yl)azetidin-2-one 5p has confirmed the molecular structure and the stereochemical outcome. The cis or trans configuration of β-lactams (5, 6) was assigned with respect to position of C3-H and C4-H.

The present study is an attempt to exploit somaclonal variation for the varietal improvement of pigeonpea [Cajanus cajan (L) Millsp.]. The pigeonpea plants were regenerated from cotyledon explants, and their progeny was screened for variability. The regenerated R1 plants exhibited a spectrum of alterations in floral morphology and architecture that were absent in the control population. The field-sown R2 plants segregated for traits such as flower color, leaf shape, seed size, color and strophiolation, flowering habit, and fertility. Tissue culture produced different mutational events resulting in both dominant and recessive alleles. Significant variation was observed for plant height, seed mass, and damage due to the insect pest Helicoverpa armigera. The R3 plants, obtained from seed of R2 generation selected for traits such as white seed coat, strophiolation, reduced plant height, seed mass and low damage due to Helicoverpa, maintained the traits when compared with the seed-derived control populations. The results indicate a definite gene for white seed coat and the possibility of additional genes for pest tolerance and high seed mass in an adapted background.

No abstract

Background: A lot of advancement has been made in the area of β-lactams in recent times. Most of the research is targeted towards the synthesis of novel β-lactams, their functionalization and exploring their biological potential. The C-3 functionalization of β-lactams has continued to attract considerable interest of the scientific community due to their utility as versatile intermediates in organic synthesis and their therapeutic applications. This has led to the significant increase in efforts towards developing efficient and economic strategies for C-3 functionalized β-lactams. Objective: The present review aims to highlight recent advancement made in C-3 functionalization of β-lactams. Conclusion: To summarize, functionalization of β-lactams at C-3 is an essential aspect of β-lactam chemistry in order to improve/modify its synthetic utility as well as biological potential. The C-3 carbocation equivalent method has emerged as an important and convenient strategy for C-3 functionalization of β-lactam heterocycles which provides a wide range of β-lactams viz. 3-alkylated β-lactams, 3-aryl/heteroarylated β-lactams, 3- alkoxylated β-lactams. On the other hand, base mediated functionalization of β-lactams via carbanion intermediate is another useful approach but their scope is limited by the requirement of stringent reaction conditions. In addition to this, organometallic reagent mediated α-alkylation of 3-halo/3-keto-β-lactams also emerged as interesting methods for the synthesis of functionalized β-lactams having good yields and diastereoselectivities.