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81.
82.
Lima Rodrigues Mahesh S. Majik Santosh G. Tilve Solimabi Wahidulla 《Tetrahedron letters》2018,59(37):3413-3415
(?)-Elemoxide, a fragrant compound was synthesised using commercially available elemol in four steps with overall yield of 32%. The cyclic ether skeleton was constructed via intramolecular hydroalkoxylation using I2 and PhSiH3 catalytic system. Also, intramolecular oxymercuration-demercuration was employed as an alternate approach for cyclization. The various regioselective strategies involving epoxidation of alkene, reduction of epoxide and intramolecular cyclization were the highlights of the work. The key intermediate diol serves as a versatile intermediate for the synthesis of elemoxide and elemene. 相似文献
83.
Puchakayala Bharath Kumar Reddy Kanakaraju Ravi Kukkamudi Mahesh Panaganti Leelavathi 《Tetrahedron letters》2018,59(45):4039-4043
A simple and convenient sequential one-pot synthesis of 1,2,3,4-tetrahydrobenzo[b][1,6] naphthyridines has been developed. The reductive amination of 2-chloro-3-formylquinolines with various amines in the presence of sodium borohydride provided the corresponding secondary amines in high yields. Further, a sequential one-pot reaction involving N-allylation and intramolecular Heck type 6-exo-trig cyclization was performed on the secondary amines to afford a range of desired 1,2,3,4-tetrahydrobenzo[b][1,6]-naphthyridine derivatives in good to high yields. 相似文献
84.
Bikash Debnath Waikhom Somraj Singh Manik Das Sanchari Goswami Mahesh Kumar Singh Debasish Maiti Kuntal Manna 《Materials Today Chemistry》2018
Alkaloids are plant secondary metabolite. They are well known nitrogen-containing natural bioactive compounds. Cutting edge research is going on alkaloids to unravel novel therapeutic approaches. Literature reveals that alkaloids contribute multiple biological activities and some alkaloids transform into active metabolites too. In this review, we have focused on marketed and experimental alkaloids. We have summarized sources and biological activities of reported alkaloids in past decades. 相似文献
85.
Jayapal P Robinson D Sundararajan M Hillier IH McDouall JJ 《Physical chemistry chemical physics : PCCP》2008,10(13):1734-1738
Multi-reference M?ller-Plesset calculations of a model of the Ni-SI state of nickel-iron hydrogenase predict a singlet rather than a triplet state for this species, and show that it is better described with a BP86 rather than a B3LYP functional. 相似文献
86.
Patil SP Mathew R Ajithkumar TG Rajamohanan PR Mahesh TS Kumaraswamy G 《The journal of physical chemistry. B》2008,112(15):4536-4544
We describe the covalent modification of the edges of laponite with organic groups and the influence of this modification on gelation behavior. We compare three materials: an unmodified laponite, a laponite edge modified with a trimethyl moiety (MLap), and an octyldimethyl moiety (OLap). Gelation is investigated using rheology and NMR T1 relaxation measurements and nuclear Overhauser enhancement spectroscopy (NOESY). MLap and OLap show qualitatively different gelation. Gelation of MLap is very similar to laponite: MLap gels over the same time scale as laponite and has about the same solid modulus, and the MLap gel is almost as transparent as laponite. In contrast, OLap gels rapidly relative to laponite and forms a weak, turbid gel. We believe that gelation in laponite and MLap results from the formation of a network of well-dispersed platelets (or a few platelets), while in OLap, gelation results from a network of stacks of several platelets. NMR relaxation measurements indicate that gelation does not affect the average relaxation of water protons. However, T1 increases marginally for the protons in the organic moieties in MLap and decreases for protons in the organic moieties in OLap. Relaxation measurements, analyses of line width, and NOESY taken together suggest that, in OLap, gelation is a consequence of association of the organic moieties on the laponite edges, and that this association strengthens with time. Thus, the time-dependent changes in NMR suggest a structural origin for the time-dependent changes in the rheological behavior. 相似文献
87.
Venkatapuram Padmavathi Annaji Venkata Nagendra Mohan Konda Mahesh 《Journal of heterocyclic chemistry》2008,45(4):1131-1138
Novel bisheterocycles, 1,2,3‐selenadiazoles, thiadiazoles and 2H‐diazaphospholes in combination with oxadiazoles, thiadiazoles and triazoles were prepared from phenacylsulfonylacetic acid methyl ester. 相似文献
88.
Venkatapuram Padmavathi Kaveti Sudheer Dandu Rangayapalle Chinna Venkata Subbaiah Konda Mahesh 《Journal of heterocyclic chemistry》2008,45(2):513-519
A new class of spiro heterocycles viz., spiropyrazolidinediones, isoxazolidinediones, pyrimidinetriones or thioxopyrimidinediones are developed from methyl 3‐aryl‐2‐(Z‐arylethenenylsulfonyl)acrylate by double Michael addition reaction with dimethyl malonate followed by cyclocondensation with appropriate nucleophiles. 相似文献
89.
Avinash S. Kumbhar Mahesh P. Mulay Subhash B. Padhye Sudam S. Tavale Vedavati G. Puranik 《Structural chemistry》2008,19(5):735-740
Crystal structure of {[Mn(salicylaldoximeH)(salicylaldoxime)]4} · 3CHCl3 1 formed by the interaction of MnCl2 · 4H2O and salicylaldoxime in a 1:1 ratio is described. The compound crystallizes in the orthorhombic space group Pbca (No 61) with the lattice parameters; a = 27.769 (3), b = 22.672 (2), c = 21.650 (2) Å, V = 13630 (2) Å3, Z = 8, R 1 = 0.0776, wR 2 = 0.2356, S = 1.164. The cluster with four Mn (III) centers formed by four terminal and four bridging salicylaldoxime ligands results in a central rotating wheel-like core with the Mn–Mn separation varying from 3.531 to 3.576 Å and with the diagonal distances being 4.156–4.165 Å. Four intramolecular H-bonds between a terminal oxime (NOH) group and the adjacent phenolate oxygen atom of another ligand stabilize the structure of the cluster. Spectral, magnetic, and cyclic voltammetry studies corroborate a stable Mn (III) tetramer. 相似文献
90.
The mechanism of the reduction of the hydrated uranyl cation, [UO2](2+), by the cytochromes G. sulfurreducens and D. acetoxidans has been studied using density functional theory calculations. We propose that the initial electron transfer step from the heme is to a cation-cation complex in the case of D. acetoxidans, but for G. sulfurreducens, it is to a single uranyl cation, which then forms a U(V)-U(VI) complex with a second uranyl cation. For both enzymes, the subsequent catalytic pathways are very similar. A U(V)-U(V) complex is formed, which then undergoes disproportionation via two successive protonation steps of one uranyl group, to give a U(VI)-U(IV) complex which dissociates to individual U(VI) and U(IV) species, the former being bound at the enzyme active site. Intermediate structures along the catalytic pathway are consistent with EXAFS data. 相似文献