Synthesis and structure determination of 7a-Aza-B-homostigmast-5-eno [7a, 7-d] tetrazole-3β-yl chloride (C29H47N4Cl)

7a-Aza-B-homostigmast-5-eno [7a, 7-d] tetrazole-3β-yl chloride (C₂₉H₄₇N₄Cl) was synthesized for its crystallographic analysis and to investigate the role of intra- and intermolecular interactions in steroids. It crystallizes in the monoclinic space group C2 with unit cell parameters: a = 38.481(2), b = 6.661(3), c = 11.111 (6) ?, β = 94.49 (4)^o; λ( MoKα) = 0.71069 ?, V = 2839(2) ?³, and Z = 4. The structure has been solved by direct methods using X-ray diffraction techniques. The final reliability index for the computed structure is 0.0597 for 1252 observed reflections. Except the five-membered ring, all other rings of the steroid nucleus exist in non-planar conformations. The structure is stabilized by C–H···N intermolecular interaction.Supplementary material CCDC-267926 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge at www.ccdc.cam.an.uk/uk/conts/retrieving.html or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, United Kingdom; Fax: $+$44(0) 1223-336033; e-mail: deposit@ccdc.cam.ac.uk.     

A chiral pool approach to the synthesis of optically active tetrahalo norbornyl building blocks

Optical antipodes of the mono- and disubstituted polyhalo norbornyl derivatives were prepared in excellent yields. The monosubstituted derivatives 7 were obtained with good enantiopurities. A kaleidoscopic change in the product formation and distribution was observed by changing the chronology of reactions.     

A structural, theoretical and coordinative evaluation of the bicyclic guanidinate derived from 1,4,6-triazabicyclo[3.3.0]oct-4-ene

Partial deprotonation of the bicyclic guanidine 1,4,6-triazabicyclo[3.3.0]oct-4-ene (Htbo) is achieved using (n)BuLi. Isolation of the resulting lithium salts has resulted in the structural characterization of the mixed anion complex {[Li(tbo)()(tboH)](2)}(infinity) (where -H = 1-(2-aminoethyl)-2-imidazolidinethione) and the partially deprotonated salt Li(6)(tbo)(6)(Htbo)(3), . The neutral guanidine Htbo reacts cleanly with AlMe(3) and ZnMe(2) to afford the organometallic complexes [Al(tbo)Me(2)](2) [](2), and Zn(3)(tbo)(4)Me(2) (). Structural characterization of these compounds enables comparison between the {5:5}-bicyclic system, [tbo](-), and the previously reported {6:6}-bicyclic system, [hpp](-) (where hppH = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine). Results indicate that delocalization within the [tbo](-) anion is restricted to the CN(2) amidinate component, with retention of electron density in the non-bonding nitrogen lone-pair. These conclusions are supported by a DFT analysis of the neutral guanidines, Htbo and hppH.     

An expeditious and environmentally friendly synthesis of 3-substituted isocoumarins using microwave irradiation

A microwave-assisted, environmentally friendly, high-yielding, time-saving synthesis of medicinally important 3-substituted isocoumarins was carried out in a single step by direct condensation of homophthalic acid with aryol and acyl chlorides under solvent-free conditions without any solid support. The synthesised isocoumarins were structurally characterised by microanalysis, 1H NMR, EI, IR and UV.     

Synthesis of polyhydroxy piperidines and their analogues: a novel approach towards selective inhibitors of alpha-glucosidase

Various polyhydroxy piperidine azasugars have been synthesized from precursors 18a and 18b, obtained in both enantiomeric forms from d-ribose. Out of these polyhydroxy piperidine azasugars, 22, 39 and 20 were found to be potent as well as selective inhibitors of alpha-glucosidase with K(i) values ranging as low as 1.07 microM, 16.4 microM, and 88.2 microM, respectively. Replacement of the hydroxy methylene moiety of (K(i) 33% at 1 mM) by an amino methylene moiety (32, K(i) 36.8 microM) showed a remarkable increase in the activity (almost 30 times). Furthermore, increasing the lipophilicity of by N-alkylation with a dodecyl group (36) showed a three-fold enhancement in the activity (K(i) 217 microM to K(i) 72.3 microM).     

Unexpected solid-state photochemistry of an alpha-thiophenyl-alpha'-thiophenyl-S,S-dioxo-substituted ketone

Samples of 2,4-dimethyl-2-(thiophen-3-yl)-4-(thiophen-3-yl-S,S-dioxo)pentan-3-one 2 were obtained by controlled MCPBA oxidation of 2,4-dimethyl-2,4-di(thiophen-3-yl)pentan-3-one 1. Rather than the expected photodecarbonylation, UV--vis irradiation of 2 led to the intramolecular 2 + 2 photocycloaddition product 5 in quantitative yields (by GC and NMR) both in solution and in crystalline solid state. Detailed X-ray powder diffraction analyses revealed that the solid-state reaction of sulfone 2 occurs with a loss of long-range order despite retaining some birefringence under polarized microscopy.     

Effects of substituents in the beta-position of 1,3-dicarbonyl compounds in bromodimethylsulfonium bromide-catalyzed multicomponent reactions: a facile access to functionalized piperidines

1,3-Dicarbonyl compounds can be converted to Mannich-type products A or highly functionalized piperidines B in the presence of a catalytic amount of bromodimethylsulfonium bromide (BDMS). The combination of aromatic aldehyde, amine, and 1,3-dicarbonyl compounds in the presence of a catalytic amount of BDMS leads to the formation of Mannich-type product A when R is a non-enolizable carbon or an alkoxy group, whereas in cases when R = CH3, the same combination yielded highly functionalized piperidines B. A synthetic study and mechanistic proposal are presented.     

Supported 12-tungstophosphoric acid as heterogeneous and recoverable catalysts for the synthesis of oxazolines,imidazolines and thiazolines under solvent-free conditions

12-Tungstophosphoric acid (TPA) supported on silica, activated carbon and poly(4-styrylmethyl)pyridinium chloride (PMP) were found to be highly efficient catalysts for the synthesis of oxazolines, imidazolines and thiazolines from the condensation of various nitriles with aminoalcohols, ethylenediamine and cisteamine, respectively. In the case of oxazolines, dicyanobenzenes were selectively converted to mono- and bis-oxazolines in the presence of these catalysts. In the reaction of dicyanobenzenes with ethylenediamine, only mono-imidazolines were produced and the remaining cyano group did not react even with long reaction times. In the case of thiazolines, only bis-thiazolines were produced in the reaction of dicyanobenzenes with cysteamine. Furthermore, these catalysts could be recovered and reused without significant loss of their activities.     

Silica supported perchloric acid （HClO4-SiO2）： A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of amidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.