β-Glucosides of steroidal unsaturated nitriles

1987 ◽  
Vol 52 (10) ◽  
pp. 2521-2533 ◽  
Author(s):  
Ivan Černý ◽  
Vladimír Pouzar ◽  
Pavel Drašar ◽  
Miroslav Havel
Keyword(s):  
Double Bond ◽  
Reaction Pathway ◽  
Trimethylsilyl Derivative ◽  
Protecting Group ◽  
Subsequent Removal ◽  
Tetrabutylammonium Fluoride ◽  
Silver Silicate ◽  
Parallel Series

Reaction of 3β-methoxymethoxy-5-pregnen-20-one (Ia) with diethyl cyanomethylphosphonate and subsequent removal of the protecting group afforded (20E)-3β-hydroxy-24-norchola-5,20(22)-diene-23-nitrile (IIIa). Besides the analogous derivative IIIb with another double bond in position 14, the fully saturated compounds IIIc and IIId with configuration 5α and 5β, respectively, were prepared similarly. Silver silicate-catalyzed glycosylation of IIIa-IIId with tetra-O-acetyl-α-D-glucopyranosyl bromide gave β-D-glucopyranosides IVa-IVd in 77-89% yield. A parallel series of hemisuccinates VIa-VId was prepared in 64-81% yields by reaction of IIIa-IIId with 2-(trimethylsilyl)ethyl hydrogen butanedioate followed by deblocking with tetrabutylammonium fluoride. The glucoside IVa was prepared also by an alternative reaction pathway starting from 3β-hydroxy-5-pregnen-20-one (VIII). Compound VIII was converted in 80% yield into the glucoside IX which, after protection as the tetra-O-(trimethylsilyl)derivative XII, was treated with diethyl cyanomethylphosphonate.

scholarly journals Synthesis and Antiproliferative Evaluation of 2-Deoxy-N-glycosylbenzotriazoles/imidazoles

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3742
Author(s):  
Caleigh S. Garton ◽  
Noelle K. DeRose ◽  
Dylan Dominguez ◽  
Maria L. Turbi-Henderson ◽  
Ashley L. Lehr ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Addition Reaction ◽  
Protecting Group ◽  
Human Breast ◽  
Lung Cancer Cell ◽  
Subsequent Removal ◽  
Anticancer Properties ◽  
Tributyltin Hydride ◽  
High Yields

A series of 2-deoxy-2-iodo-α-d-mannopyranosylbenzotriazoles was synthesized using the benzyl, 4,6-benzylidene and acetyl protected D-glucal in the presence of N-iodosuccinimide (NIS). Subsequent removal of the iodine at the C-2 position using tributyltin hydride under free radical conditions afforded the 2-deoxy-α-d-glucopyranosylbenzotriazoles in moderate to high yields. This method was extended to the preparation of substituted 2-deoxy-β-d-glucopyranosylimidazoles as well. The stereoselectivity of the addition reaction and the effect of the protecting group and temperature on anomer distribution of the benzotriazole series were also investigated. The anticancer properties of the newly synthesized compounds were evaluated in a series of viability studies using HeLa (human cervical adenocarcinoma), human breast and lung cancer cell lines. The N-[3,4,6-tri-O-benzyl-2-deoxy-α-d-glucopyranosyl]-1H-benzotriazole and the N-[3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl]-2H-benzotriazole were found to be the most potent cancer cell inhibitors at 20 µM concentrations across all four cell lines.

scholarly journals Sunscreen-Assisted Selective Photochemical Transformations

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2125
Author(s):  
Or Eivgi ◽  
N. Gabriel Lemcoff
Keyword(s):  
Photochemical Reaction ◽  
Reaction Pathway ◽  
General Procedure ◽  
Molar Absorptivity ◽  
Photochemical Reactions ◽  
The Other ◽  
Protecting Group ◽  
Selective Reaction ◽  
Photochemical Transformations ◽  
Photolabile Protecting Group

In this review, we describe a simple and general procedure to accomplish selective photochemical reaction sequences for two chromophores that are responsive to similar light frequencies. The essence of the method is based on the exploitation of differences in the molar absorptivity at certain wavelengths of the photosensitive groups, which is enhanced by utilizing light-absorbing auxiliary filter molecules, or “sunscreens”. Thus, the filter molecule hinders the reaction pathway of the least absorbing molecule or group, allowing for the selective reaction of the other. The method was applied to various photochemical reactions, from photolabile protecting group removal to catalytic photoinduced olefin metathesis in different wavelengths and using different sunscreen molecules. Additionally, the sunscreens were shown to be effective also when applied externally to the reaction mixture, avoiding any potential chemical interactions between sunscreen and substrates and circumventing the need to remove the light-filtering molecules from the reaction mixture, adding to the simplicity and generality of the method.

Synthesis of Some 2'-C-Alkyl Derivatives of 9-(2-Phosphonomethoxyethyl)adenine and Related Compounds

1994 ◽  
Vol 59 (9) ◽  
pp. 2069-2094 ◽  
Author(s):  
Hana Dvořáková ◽  
Antonín Holý ◽  
Ivan Rosenberg
Keyword(s):  
Reaction Pathway ◽  
Sodium Hydride ◽  
Amino Group ◽  
Trimethylsilyl Derivative ◽  
Phosphonic Acids ◽  
Alkyl Derivatives ◽  
Hydrolysis Of ◽  
Trifluoromethyl Derivative ◽  
Derivatives Of ◽  
Related Compounds

To study the effect of β-substitution in 2'-alkyl derivatives of 9-(2-phosphonomethoxyethyl)adenine (Ia) on the antiviral activity or group specificity, these derivatives were synthesized. 9-(2-Hydroxyalkyl)adenines VIII were prepared by alkylation of adenine with suitably substituted oxiranes XIII or 2-hydroxyalkyl p-toluenesulfonates IV and VI. After protection of the adenine amino group by benzoylation (compounds IX) or amidine formation (compounds X), the intermediates were alkylated with diisopropyl p-toluenesulfonyloxymethanephosphonate (XI) in the presence of sodium hydride. After deprotection, the obtained phosphonate diesters XII were converted into phosphonic acids I by transsilylation and hydrolysis. This synthetic scheme was used for the preparation of ethyl (Ie), propyl (If), 2-propyl (Ig), 2-methylpropyl (Ih), cyclopropyl (Ii), cyclohexyl (Ij), benzyl (Ik) and phenyl (Il) derivatives. The 2'-trifluoromethyl derivative XXIIa was prepared analogously from 9-(2-hydroxy-3,3,3-trifluoropropyl)adenine (XXa), obtained by alkylation of adenine sodium salt with 2-hydroxy-3,3,3-trifluoropropyl bromide. 2'-Trimethylsilyl derivative XIXa was obtained by alkylation of adenine with 2-diisopropylphosphonomethoxy-3-(4-toluenesulfonyloxy)propyltrimethylsilane (XVII) followed by transsilylation and hydrolysis of diester XVIIIa. 2,6-Diaminopurine derivatives XVIIId and XXIIb were obtained analogously. 9-(3-Phosphonomethoxybutyl)adenine (XXVIII) and 9-(2-methyl-2-phosphonomethoxypropyl)adenine (XXXV) were prepared from the corresponding hydroxy derivatives XXVIb and XXXII, respectively, by the same reaction pathway as derivatives I.

A Concise Synthesis of 24,25-Dihydro-6-epi-Monanchosterol A

Synlett ◽  
2021 ◽  
Author(s):  
Hans-Günther Schmalz ◽  
Ömer Taspinar ◽  
Vladimir Kjartan Stojadinovic ◽  
Jörg-Martin Neudörfl
Keyword(s):  
Double Bond ◽  
Title Compound ◽  
Protecting Group ◽  
Structural Analogue ◽  
X Ray ◽  
X Ray Crystallography ◽  
Anti Inflammatory ◽  
Aldol Addition ◽  
Optimized Conditions

AbstractWe report the first synthetic entry to a steroid with an unusual bicyclo[4.3.1]dec-3-en-10-one A/B ring substructure as a close structural analogue of the anti-inflammatory monanchosterols. Under optimized conditions, regioselective cis-dihydroxylation of the Δ5-double bond of 7-dehydrocholesterol and subsequent Criegee oxidation yields the corresponding 5,6-seco-steroid as a pure Z-isomer which upon treatment with K2CO3 in MeOH diastereoselectively affords 24,25-dihydro-6-epi-monanchosterol A through intramolecular aldol addition (cyclization). The developed three-step sequence proceeds in 17% overall yield without the need of any protecting group. The title compound was characterized by X-ray crystallography.

The transformation of levopimaric acid into warburganal

1988 ◽  
Vol 66 (7) ◽  
pp. 1675-1685 ◽  
Author(s):  
William A. Ayer ◽  
Francisco X. Talamas
Keyword(s):  
Double Bond ◽  
Formic Acid ◽  
Sodium Methoxide ◽  
Resin Acid ◽  
Starting Material ◽  
Protecting Group ◽  
Methyl Group ◽  
Levopimaric Acid

The chiral resin acid levopimaric acid (1), isolated from pine oleoresin, is used as a starting material for the synthesis of (−)-warburganal (2). The synthesis proceeds via the endoperoxide of methyl levopimarate, which after ozonolysis, protection of the resulting aldehyde function, reduction, and treatment with sodium methoxide provides the tetranorditerpenoid 12a. The hemiacetal 12a is then transformed to a mixture of hemithioacetals. At this point the carbomethoxyl group at C-4 is reduced to a methyl group, and then a C-11, C-12 double bond is introduced. Ozonolysis followed by elimination of formic acid provides a mixture of olefins (27) that is hydroxylated at C-9. Removal of the protecting group then gives (−)-warburganal (2). The sequence requires 15 steps and the overall yield from levopimaric acid to warburganal is 2.7%.

Synthesis of some substituted 4-Aminobut-2-enoic acids as analogues of the neurotransmitter GABA

1978 ◽  
Vol 31 (10) ◽  
pp. 2283 ◽  
Author(s):  
RD Allan ◽  
B Twitchin
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Double Bond ◽  
Magnetic Resonance ◽  
Unsaturated Acid ◽  
Proton Magnetic Resonance ◽  
Liquid Ammonia ◽  
Protecting Group ◽  
Chemical Studies ◽  
Secondary Amino

Allylic bromination of a series of α,β-unsaturated acids with N- bromosuccinimide gave crude products which could be aminated conveniently in liquid ammonia to prepare the substituted 4-aminobut-2- enoic acid (4-aminocrotonic acid) derivatives (4a-f) in low to moderate yields. The assignment of the trans configuration of the carboxyl and aminomethyl groups about the double bond of the amino acid products is supported by chemical studies and proton magnetic resonance spectral data. The procedure worked conveniently with methylamine to give the unsaturated secondary amino acids (8a,b). Methylamine was also shown to remove a phthalimido protecting group cleanly in the presence of an α,β-unsaturated acid functionality.

The synthesis of oligoribonucleotides. II. The use of silyl protecting groups in nucleoside and nucleotide chemistry. VII

1978 ◽  
Vol 56 (21) ◽  
pp. 2768-2780 ◽  
Author(s):  
Kelvin K. Ogilvie ◽  
Serge L. Beaucage ◽  
Aria L. Schifman ◽  
Nicole Y. Theriault ◽  
Krishan L. Sadana
Keyword(s):  
Protecting Groups ◽  
Protecting Group ◽  
Rapid Preparation ◽  
Tetrabutylammonium Fluoride

The synthesis of oligonucleotides derived from uridine and adenosine using the tert-butyldimethylsilyl protecting group and the trichloroethylphosphorodichloridite condensation procedure is described. These procedures involve rapid preparation of protected starting materials and equally rapid condensation of units to form nucleotides. Optimum yields using collidine as base in tetrahydrofuran as solvent are between 65 and 80%. The utility of the procedure is rendered complete by the capability to remove both the phosphate protecting groups and the alkylsilyl groups in a single 30 min step using tetrabutylammonium fluoride in tetrahydrofuran.

Stereochemical and Mechanistic Aspects of the Aprotic Conjugate Addition Reactions of the Carbanions of Octenyl Sulfides and Octenyl Thiocarbamates With 4-Tert-Butoxycyclopent-2-Enone in the Presence of Hexamethylphosphoric Triamide

1987 ◽  
Vol 40 (5) ◽  
pp. 937 ◽  
Author(s):  
MR Binns ◽  
RK Haynes
Keyword(s):  
Double Bond ◽  
Chemical Shift ◽  
Sulfur Atom ◽  
Reaction Pathway ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Coupling Constant ◽  
Hexamethylphosphoric Triamide ◽  
Major Reaction ◽  
Phosphoric Triamide

The carbanions of (E)- and (Z)-1-(pheny1thio)oct-2-ene, (E)-1-(methy1thio)- and 1-(t-butyl- thio )oct-2-ene, N,N-dimethyl S-[(E)-oct-2-enyllthiocarbamate and (E)-oct-2-enyl benzothiazole undergo conjugate addition to 4-t-butoxycyclopent-2-enone in the presence of hexamethyl - phosphoric triamide ( hmpa ) in tetrahydrofuran at -70� to give as predominant products diastereomeric mixtures of syn and anti allylic sulfides arising from reaction through C1 of the octenyl carbanions. Also formed in some cases are small amounts of diastereomeric mixtures of syn and anti vinylic sulfides arising from reaction through C3 of the octenyl carbanions. In the absence of the hmpa, carbonyl addition is the major reaction pathway of the carbanions of each of the (E)- and (Z)- octenyl thiocarbamates. The constitutions and stereostructures of all the products have been established through chemical shift and coupling constant correlations of their IH n.m.r. data obtained at 400 MHz. The relative proportions of the regioisomeric allylic and vinylic sulfides are dependent both upon the nature of the non-allylic substituent attached to the sulfur atom, and the geometry of the double bond in the starting octenyl sulfide. While there is no apparent connection between the electronic properties or sizes of the non-allylic substituent and the diastereomer ratios of the allylic and vinylic sulfides, it is noted that the (2)-(phenylthio) octene delivers an allylic sulfide mixture enriched in the syn isomer. It is concluded that the carbanions are configurationally stable at-70� and that the configurations of the vinylic sulfides reflect the configurations of the carbanions from which they are derived. It is also concluded that the reactions proceed under orbital control, as this best accounts for the formation of the vinylic sulfides and is in accord with the results of STO-3G calculations carried out on a series of sulfur-bearing allylic carbanions . The likely angle of attack of the carbanions on the enone system is briefly discussed in terms of a published model relating to the attack of a simple nucleophile on an electrophilic double bond.

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