Participation of the oxygen-containing substituent in alkaline saponification of 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestane derivatives

1986 ◽  
Vol 51 (4) ◽  
pp. 930-936 ◽  
Author(s):  
Helena Velgová
Keyword(s):  
Hydroxy Group ◽  
Acetoxy Group ◽  
Epoxide Ring ◽  
Main Component ◽  
Hydroxy Groups

Alkaline saponification of the 3-acetoxy group in 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5βcholestane derivatives I-VI was studied. It was found that the 3α- and 4aα-hydroxy groups participated in the cleavage of the 5β,6β-epoxide ring in the derivatives II-IV: the 5(O)n participation by the 3α-hydroxy group (the derivatives III and IV) led to formation of the transannular 3α,5α-epoxides XII and XIV whereas the participation by the 4aα-hydroxy group (the derivatives II and IV) gave rise to the 4aα,5α-epoxides IX and XV. The 5(O)n participation by the 3α-hydroxy group predominated over the preparation by the 4aα-hydroxy group. In the case of the 4a-keto epoxides V and VI the retroaldol-aldol type isomerization led to formation of 3β-hydroxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-one as the main component of the equilibration mixtures.

scholarly journals Linking Aromatic Hydroxy Metabolic Functionalization of Drug Molecules to Structure and Pharmacologic Activity

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2119 ◽  
Author(s):  
Babiker El-Haj ◽  
Samrein Ahmed ◽  
Mousa Garawi ◽  
Heyam Ali
Keyword(s):  
Benzene Ring ◽  
Hydroxy Group ◽  
Water Solubility ◽  
Parent Drug ◽  
Drug Action ◽  
Alkoxy Group ◽  
Drug Molecules ◽  
Drug Classes ◽  
Pharmacologic Activity ◽  
Hydroxy Groups

Drug functionalization through the formation of hydrophilic groups is the norm in the phase I metabolism of drugs for the modification of drug action. The reactions involved are mainly oxidative, catalyzed mostly by cytochrome P450 (CYP) isoenzymes. The benzene ring, whether phenyl or fused with other rings, is the most common hydrophobic pharmacophoric moiety in drug molecules. On the other hand, the alkoxy group (mainly methoxy) bonded to the benzene ring assumes an important and sometimes essential pharmacophoric status in some drug classes. Upon metabolic oxidation, both moieties, i.e., the benzene ring and the alkoxy group, produce hydroxy groups; the products are arenolic in nature. Through a pharmacokinetic effect, the hydroxy group enhances the water solubility and elimination of the metabolite with the consequent termination of drug action. However, through hydrogen bonding, the hydroxy group may modify the pharmacodynamics of the interaction of the metabolite with the site of parent drug action (i.e., the receptor). Accordingly, the expected pharmacologic outcome will be enhancement, retention, attenuation, or loss of activity of the metabolite relative to the parent drug. All the above issues are presented and discussed in this review using selected members of different classes of drugs with inferences regarding mechanisms, drug design, and drug development.

scholarly journals Crystal structure oftrans-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)oxamide methanol monosolvate

2016 ◽  
Vol 72 (7) ◽  
pp. 918-921
Author(s):  
Miguel-Ángel Velázquez-Carmona ◽  
Sylvain Bernès ◽  
Francisco Javier Ríos-Merino ◽  
Yasmi Reyes Ortega
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Hydroxy Group ◽  
Molecular Conformation ◽  
Methanol Molecule ◽  
Molecular Symmetry ◽  
Methyl Group ◽  
Supramolecular Motifs ◽  
Butyl Group ◽  
Hydroxy Groups

The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérezet al.(2000).J. Organomet. Chem.614–615, 283–293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the molecular symmetry of the oxamide, which remains centrosymmetric, nor the molecular conformation. However, the unsolvated molecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hydroxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4):0.304 (4); onetert-butyl group is disordered by rotation about the C—C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hydroxy groups and the solvent of crystallization allows the formation of numerous supramolecular motifs using four hydrogen bonds, with N—H and O—H groups as donors and the oxamide and methanol molecule as acceptors.

scholarly journals Threefold helical assembly via hydroxy hydrogen bonds: the 2:1 co-crystal of bicyclo[3.3.0]octane-endo-3,endo-7-diol and bicyclo[3.3.0]octane-endo-3,exo-7-diol

2021 ◽  
Vol 77 (3) ◽  
pp. 270-276
Author(s):  
Isa Y. H. Chan ◽  
Mohan M. Bhadbhade ◽  
Roger Bishop
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydroxy Group ◽  
Network Structure ◽  
General Position ◽  
Three Dimensional ◽  
Screw Axis ◽  
Hydroxy Groups

Reduction of bicyclo[3.3.0]octane-3,7-dione yields a mixture of the endo-3,endo-7-diol and endo-3, exo-7-diol (C8H14O2) isomers (5 and 6). These form (5)2·(6) co-crystals in the monoclinic P21/n space group (with Z = 6, Z′ = 1.5) rather than undergoing separation by means of fractional recrystallization or column chromatography. The molecule of 5 occupies a general position, whereas the molecule of 6 is disordered over two orientations across a centre of symmetry with occupancies of 0.463 (2) and 0.037 (2). Individual diol hydroxy groups associate around a pseudo-threefold screw axis by means of hydrogen bonding. The second hydroxy group of each diol behaves in a similar manner, generating a three-dimensional hydrogen-bonded network structure. This hydrogen-bond connectivity is identical to that present in three known helical tubuland diol–hydroquinone co-crystals, and the new crystal structure is even more similar to two homologous aliphatic diol co-crystals.

scholarly journals Crystal structure of 2,4-di-tert-butyl-6-(hydroxymethyl)phenol

2016 ◽  
Vol 72 (11) ◽  
pp. 1614-1617
Author(s):  
Ane I. Aranburu Leiva ◽  
Sophie L. Benjamin ◽  
Stuart K. Langley ◽  
Ryan E. Mewis
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Hydroxy Group ◽  
Chair Conformation ◽  
Alcohol Group ◽  
Phenolic Oxygen ◽  
Compound C ◽  
Pendant Arm ◽  
Phenol Hydroxy Group ◽  
Hydroxy Groups

The title compound, C15H24O2, is an example of a phenol-based pendant-arm precursor. In the molecule, the phenol hydroxy group participates in an intramolecular O—H...O hydrogen bond with the pendant alcohol group, forming anS(6) ring. This ring adopts a half-chair conformation. In the crystal, O—H...O hydrogen bonds connect molecules related by the 31screw axes, forming chains along thecaxis. The C—C—O angles for the hydroxy groups are different as a result of the type of hybridization for the C atoms that are involved in these angles. The C—C—O angle for the phenol hydroxy group is 119.21 (13)°, while the angle within the pendant alcohol is 111.99 (13)°. The bond length involving the phenolic oxygen is 1.3820 (19) Å, which contrasts with that of the alcoholic oxygen which is 1.447 (2) Å. The former is conjugated with the aromatic ring and so leads to the observed shorter bond length.

scholarly journals Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

2022 ◽  
Vol 18 ◽  
pp. 95-101
Author(s):  
Sandeep Kumar ◽  
Jyotirmoy Maity ◽  
Banty Kumar ◽  
Sumit Kumar ◽  
Ashok K Prasad
Keyword(s):  
Hydroxy Group ◽  
Chemical Method ◽  
Secondary Hydroxy Group ◽  
Synthetic Pathway ◽  
Conformationally Restricted ◽  
Hydroxy Groups ◽  
Azt Analogues

Conformationally restricted diastereomeric homoarabinofuranosylpyrimidines (AZT analogue), i.e., (5′R)-3′-azido-3′-deoxy-2′-O,5′-C-bridged-β-ᴅ-homoarabinofuranosylthymine and -uracil had been synthesized starting from diacetone ᴅ-glucofuranose following chemoenzymatic and chemical routes in 34–35% and 24–25% overall yields, respectively. The quantitative and diastereoselective acetylation of primary hydroxy over two secondary hydroxy groups present in the key nucleoside precursor was mediated with Lipozyme® TL IM in 2-methyltetrahydrofuran following a chemoenzymatic pathway. Whereas, the protection of the primary hydroxy over the lone secondary hydroxy group in the key azido sugar precursor was achieved using bulky tert-butyldiphenylsilyl chloride (TBDPS-Cl) in pyridine in 92% yield following a chemical synthetic pathway. The chemoenzymatic method was found to be superior over the chemical method in respect of the number of synthetic steps and overall yield of the final product.

Epoxidation of trans-4-Aminocyclohex-2-en-1-ol Derivatives: Competition of Hydroxy-Directed and Ammonium-Directed Pathways

2015 ◽  
Vol 68 (4) ◽  
pp. 610 ◽  
Author(s):  
Méabh B. Brennan ◽  
Stephen G. Davies ◽  
Ai M. Fletcher ◽  
James A. Lee ◽  
Paul M. Roberts ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Relative Rate ◽  
Ammonium Ion ◽  
Epoxide Ring ◽  
Hydrogen Bond Donor ◽  
Epoxidation Reaction ◽  
Sterically Demanding ◽  
Tertiary Amino ◽  
Directing Group

N-Substituted trans-4-aminocyclohex-2-en-1-ols undergo epoxidation upon treatment with Cl3CCO2H followed by meta-chloroperbenzoic acid (m-CPBA) via competitive pathways resulting from hydrogen-bonding delivery by both the hydroxy group and the in situ formed ammonium ion. The absence of epoxide ring-opening in these reactions renders these substrates a unique platform for analysing the effect of the two competing directing groups on the rate of the epoxidation reaction: the diastereoisomeric ratio of the epoxide products is also the ratio of the rate constants describing the competing epoxidation processes (the group with the higher directing ability dominating the stereochemical course of the reaction). Analysis of the diastereoisomeric epoxide mixtures obtained from these reactions allowed the following order of directing group ability to be defined: NHBn >> NMeBn > OH > NBn2. The large difference in rate between the secondary and tertiary amino groups is consistent with superior directing ability of the former due to the presence of two hydrogen-bond donor sites on the secondary ammonium ion and/or an increased conformational flexibility to adopt an optimum geometry. The rate of an ammonium-directed epoxidation proceeds ~10 times slower in the presence of an allylic hydroxy group than in its absence, consistent with the presence of the additional, inductively electron-withdrawing heteroatom abating the nucleophilicity of the olefin. The relative rate of the hydroxy-directed epoxidation process in the presence of a more sterically demanding ammonium substituent is greater than that in the presence of a less sterically demanding one: this effect is attributed to an increased bias for the half-chair conformer in which the bulky ammonium substituent and, hence, the hydroxy group occupy pseudo-equatorial sites, thus allowing the latter to direct the reaction more efficiently.

scholarly journals Purification and characterization of a novel dimeric 20 α-hydroxysteroid dehydrogenase from Tetrahymena pyriformis

1994 ◽  
Vol 297 (1) ◽  
pp. 195-200 ◽  
Author(s):  
A Inazu ◽  
K Sato ◽  
T Nakayama ◽  
Y Deyashiki ◽  
A Hara ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Carbonyl Compounds ◽  
Specific Activity ◽  
Reductase Activity ◽  
Tetrahymena Pyriformis ◽  
Hydroxysteroid Dehydrogenase ◽  
Purification And Characterization ◽  
Reductase Inhibitors ◽  
Hydroxy Groups

Tetrahymena pyriformis was found to exhibit high NADPH-dependent 20-oxosteroid reductase activity that converted 17 alpha-hydroxyprogesterone into 17 alpha,20 alpha-dihydroxypregn-4-en-3-one. The enzyme was purified 400-fold from the cytosolic fraction. The purified enzyme with a specific activity of 6.4 mumol/min per mg of protein had an isoelectric point of 4.9 and M(r) of 68,000, and was composed of two subunits of equal size. The N-terminal sequence was determined to be LAKTVPLNDGTNFPIFGG. The enzyme reduced pregnanes and pregnanes possessing a 17 alpha-hydroxy group to a greater extent than those without the hydroxy group, and oxidized 20 alpha-hydroxy groups of the steroids in the presence of NADP+. The Km values for 17 alpha-hydroxyprogesterone and 17 alpha-hydroxypregnenolone were 2.9 and 3.4 microM respectively. Although the enzyme was inactive towards androgens and oestrogens with 3- or 17-oxo groups, it reduced several nonsteroidal carbonyl compounds and oxidized trans-benzene dihydrodiol. The enzyme activity was inhibited by synthetic oestrogens, barbiturates, aldose reductase inhibitors and quercitrin. Thus, this enzyme is a novel form of 20 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.149) which structurally and functionally differs from the mammalian and bacterial enzymes.

A One- and Two-Dimensional 1H and 13C N.M.R. Study of Some Lichen Triterpenoids of the Pyxinol Group

1990 ◽  
Vol 43 (2) ◽  
pp. 411 ◽  
Author(s):  
AL Wilkins ◽  
JA Elix ◽  
AA Whitton
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxy Group ◽  
Furan Ring ◽  
Chemical Shifts ◽  
Carbonyl Oxygen ◽  
Ring System ◽  
Acetoxy Group ◽  
Two Dimensional ◽  
Complete Assignment

A complete assignment of the 13C and 1H n.m.r. resonances of the lichen triterpenoids, pyxinol, 3,25-di-O-acetylpyxinol and 3,12,25-tri-O-acetylpyxinol has been achieved by using a combination of one- and two-dimensional n.m.r. data and T1 values. Hydrogen bonding between the 12β- hydroxy group and the carbonyl oxygen of the 25-acetoxy group of 3,25- di-O-acetylpyxinol leads to the furan ring system adopting a� conformation different from that adopted by 25-hydroxy analogues, hence differing chemical shifts are observed for some of the carbons of rings C and D and the furan ring.

scholarly journals Linking Aromatic Hydroxy Metabolic Functionalization of Drug Molecules to Structure and Pharmacologic Activity

2018 ◽  
Author(s):  
Babiker M. El-Haj ◽  
Samrein B.M. Ahmed ◽  
Mousa A. Qarawi ◽  
Heyam S. Ali
Keyword(s):  
Benzene Ring ◽  
Hydroxy Group ◽  
Water Solubility ◽  
Parent Drug ◽  
Drug Action ◽  
Alkoxy Group ◽  
Drug Molecules ◽  
Drug Classes ◽  
Pharmacologic Activity ◽  
Hydroxy Groups

Drug functionalization through formation of hydrophilic groups is the norm in phase I metabolism of drugs for modification of drug action. The reactions involved are mainly oxidative catalyzed mostly by CYP isoenzymes. The benzene ring, as phenyl or fused with other rings, is the most common hydrophobic pharmacophoric moiety in drug molecules. On the other hand the alkoxy group (mainly methoxy) bonded to the benzene ring assumes an important and sometimes essential pharmacophoric status in some drug classes. Upon metabolic oxidation, both moieties, i.e. the benzene ring and the alkoxy group, produce hydroxy groups; the products are arenolic in nature. Through a pharmacokinetic effect, the hydroxy group enhances the water solubility and elimination of the metabolite with the consequent termination of drug action. However, through hydrogen bonding, the hydroxy group may modify the pharmacodynamics of the interaction of the metabolite with the site of parent drug action (i.e. the receptor). Accordingly, the expected pharmacologic outcome will be enhancement, retaining, attenuation, or loss of activity of the metabolite relative to the parent drug. All the above issues have been presented and discussed in this review using selected members of different classes of drugs with inferences regarding mechanisms, drug design and drug development.

Regioselective Deacetylation of Fully Acetylated Mono- and Di-Saccharides With Hydrazine Hydrate

1996 ◽  
Vol 49 (3) ◽  
pp. 293 ◽  
Author(s):  
R Khan ◽  
PA Konowicz ◽  
L Gardossi ◽  
M Matulova ◽  
S Degennaro
Keyword(s):  
Hydrazine Hydrate ◽  
Hydroxy Group ◽  
Lower Yield ◽  
Free Hydroxy Group ◽  
Regioselective Deacetylation ◽  
Hydroxy Groups ◽  
Selective Deacetylation

Selective deacetylation reactions of the peracetylated reducing disaccharides (1), (5), (9), (15), β-D- glucopyranose (17) and 2-acetamido-2-deoxy-β-D-glucopyranose (19), with 1.2 equiv. Of hydrazine hydrate in acetonitrile, gave predominantly the corresponding heptaacetates (2), (6), (10), (16), the tetraacetate (18) and the triacetate (20), with the free hydroxy group at C1. Reaction of (1) with 1.2 equiv. of hydrazine hydrate in N,N- dimethylformamide also afforded the heptaacetate (2), but in lower yield. When reactions of (1), (5) and (9) were performed with 2.5 equiv. of hydrazine hydrate, deacetylation also occurred at other positions to afford the corresponding hexaacetates (3), (7), (11) and (12), with hydroxy groups at C 1,2 or C 1,3, and the pentaacetates (4), (8) and (13), with hydroxy groups at C 1,2,3. Maltose octaacetate (9), in addition, yielded the tetraacetate (14) in which the free hydroxy groups were located at C1,2,2',3. Compound (15) on treatment with 2.5 equiv. of hydrazine hydrate afforded an intractable mixture. The reaction of methyl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside (21) with 2.5 equiv. of hydrazine hydrate gave the 3,4,6-triacetate (22), a mixture of the 2,6- and the 3,6-diacetates (23) and (24), respectively, the 4,6-diacetate (25), and the 6-acetate (26).

Sign in / Sign up

Export Citation Format

Share Document