3-monosubstituted Derivatives Research Articles

Regioselectivity in the reactions of N-(polychloroethylidene)-sulfonamides with 1H-pyrrole and 1-methyl-1H-pyrrole

N-(2,2,2-Trichloroethylidene)arenesulfonamides react with 1H-pyrrole and 1-methyl-1H-pyrrole to give the corresponding N-[2,2,2-trichloro-1-(1H-pyrrol-2-yl)ethyl]arenesulfonamides. The reaction of N-(2,2,2-trichloroethylidene)trifluoromethanesulfonamide with pyrrole leads to a mixture of 2-mono-and 2,5-disubstituted pyrroles, whereas in the reaction with 1-methyl-1H-pyrrole only the 2-substituted compound is formed. N-(2,2-Dichloro-2-phenylethylidene)-4-methylbenzenesulfonamide reacts with 1H-pyrrole to form N-[2,2-dichloro-2-phenyl-1-(1H-pyrrol-2-yl)ethyl]-4-methylbenzenesulfonamide, and its reaction with 1-methyl-1H-pyrrole gives a mixture of 2-and 3-monosubstituted derivatives. The results of quantum-chemical calculations of the initial reactants and products indicate that the process is orbital-controlled. A good agreement is observed between the experimental data and theoretical conclusions concerning the dependence of the reaction regioselectivity on the nature of substituents in the electrophile molecule.

Azadithiolates cofactor of the iron-only hydrogenase and its PR 3-monosubstituted derivatives: Synthesis, structure, electrochemistry and protonation

The core structure (μ-SCH 2) 2NH[Fe 2(CO) 6] ( 5) of Fe-only hydrogenases active site model has been synthesized by the condensation of iron carbonyl sulfides, formaldehyde and silyl protected amine. Its monosubstituted complexes (μ-SCH 2) 2NH[Fe 2(CO) 5PR 3] (R = Ph ( 6), Me ( 7)) were accordingly prepared. The coordination configurations of 5 and 6 were characterized by X-ray crystallography. Protonation of complex 7 to form the N-protonated product occurs in an acetonitrile solution upon addition of triflic acid. The redox properties of these model complexes were studied by cyclic voltammetry.

Modification of the Intact Retinoid Structure in the Cyclohexenyl Region: Alkylation of Methyl 4-Oxoretinoate

Alkylation of methyl 4-oxoretinoate under kinetic-control conditions gives predominantly 3-alkyl-4-oxoretinoates. 3,3-Disubstituted 4-oxoretinoates are obtained similarly from the 3-monosubstituted derivatives, although introduction of the second substituent is more difficult. Evidence has been obtained for a much slower rate of alkylation α to the ester group.

Nuclear Quadrupole Coupling Constant and Conformational Studies

A molecular conformation study on three 3-monosubstituted derivatives of propene has been carried out by evaluating the EFG at the site of the halogen nucleus using a semi-empirical LCAO-MO-SCF method. Calculations are performed on several conformers at INDO and CNDO level, using “sp” and “spd” valence basis sets, with Slater type orbitals as the basis functions. The results obtained for various conformers indicate that the nuclear quadrupole coupling constant is practically independent of the orientation of the CH2X group (X = Cl, Br and I) (Figure 1). The mean value of e2 Qqzz/h (averaged over all conformers) in each system matches favourably with the experimental value, despite the severe approximations that are inherent in the semi-empirical theory as well as in its application in the evaluation of the EFG.

The kinetics and mechanisms of additions to olefinic substances. Part 15. Chlorination of cholest-5-ene and its 3-substituted derivatives, including cholest-5-en-3-one; factors affecting the ? : ? ratio for electrophilic attack, and for product formation, in cholest-5-enes

Reactions of cholest-5-ene or its 3β-substituted derivatives with chlorine in chloroform or chlorobenzene give as kinetically controlled products the expected 5α,5β-dichloride, accompanied by the isomeric 5β,6α-dichloride as a minor component. The proportion of the latter decreases with the electron-withdrawing power of the 3β-substituent. Neither added pyridine nor added chloride ion affects the product proportions significantly. Cholest-5-en-3-one, on the other hand, when treated with chlorine in chlorobenzene containing 2-methyloxiran gives not only the expected 5α,6β-dichloride but also much 6α- and 6β-chlorocholest-4-en-3-one. Comparison with the results for 4β-deuteriocholest-5-ene shows that the formation of 6α-chlorocholest-4-en-3-one involves mainly displacement of the 4β-hydrogen atom, and that the formation of its 6β-isomer involves mainly but not exclusively displacement of the 4β-hydrogen atom. Similar products are obtained in deuteriochloroform containing pyridine; in acetic acid, substitution is accompanied by little addition and much unidentified material The results are compared with the corresponding results for bromination, epoxidation, and iodination. It is argued that halogenation of cholest-5-en-3-one differs from that of cholest-5-ene and its 3-monosubstituted derivatives in the ratio of attack on the α- and β-faces of the molecule for two main reasons: because of the availability of a concerted pathway for substitution involving the chair conformation of ring A of the enone, and because in non-concerted pathways for addition and substitution, ring A of the intermediate halogenonium ion derived from the enone can reach a boat conformation. Two types of AdE3 additions having different stereochemical preferences can also be recognised.

Nucleophilic addition of difunctional reagents to 2,3-dichlorobenzo[b]thiophene 1,1-dioxide

The nucleophilic reactions of 2,3-dichlorobenzo[b]thiophene 1,1-dioxide with α- and β-glycols, α-diamines, and α-amino alcohols proceed with cleavage of hydrogen chloride to give the previously unknown 3-monosubstituted derivatives of 2-chlorobenzo[b]thiophene 1,1-dioxide. The second functional group (the hydroxyl group in amino alcohols) does not enter into the reaction.

Influence of the 17 beta-hydroxyl group of androstane compounds in promotion of growth in the hypophysectomized female rat.

Studies by Huggins and Jensen (1954) on the participation of functional groups of the steroid molecule in growth-promoting processes have shown that androstan-17β-ol, but not androstan-17-one or any of the 3-monosubstituted derivatives, shared the ability of testosterone and certain 3,17-dioxygenated androstane compounds to promote growth of the vaginal epithelium and uterus in the hypophysectomized rat. Although these investigators suggested that the 17β-hydroxyl group of the androstane molecule plays a key role in the promotion of growth, there remains some uncertainty whether the monofunctional steroid (androstan-17β-ol) is biologically active per se, or whether an oxygenated function at position 3 is introduced in vivo, so that it is actually a difunctional steroid which is the growth-promoting agent. Since the fluorine atom at C3 is rather tightly bound and oxj’genation at this site seems unlikely, two 3β-fluorosteroids, 3β-fluorandrostan-17β-ol and 3β-fluorandrostan-17-one, were compared with andros...