On the Chemistry of Ingenol, III [1] Synthesis of 3-Deoxy-3-oxoingenol, Some 5-Esters and of Ethers and Acetals of Ingenol

1982 ◽  
Vol 37 (12) ◽  
pp. 1640-1647 ◽  
Author(s):  
Bernd Sorg ◽  
Erich Hecker
Keyword(s):  
Good Yield ◽  
Protecting Groups ◽  
Silyl Ether ◽  
Subsequent Removal ◽  
Mouse Ear

3-Deoxy-3-oxoingenol (3) was prepared from ingenol-5,20-acetonide (25) by oxidation and subsequent removal of the acetonide. 3 was acylated to give homologous 5,20-diacylates 5-9. From these the 5-monoacylates 14, 15 and 17 were obtained in only moderate yields. Therefore the 20-silyl ether 10 (prepared from 3) was acylated. After smooth removal of the silyl ether the homologous 5-acylates 16. 18 and 19 resulted in good yield. The 5,20-dibutyrate 6 and all 5-acylates prepared (14-19) showed no irritant activity on the mouse ear. The 3-oxo-5-acylates 14-19 could not be reduced to give ingenol-5-acylates (24). Therefore various ingenol derivatives, 29-32, with suitable protected hydroxyl functions as well as the corresponding 5-clecanoates 35-38 were synthesized. The protecting groups of the derivatives 35-38 could however not be cleaved off to yield ingenol-5- decanoate (24)

Protecting Groups

2008 ◽  
Author(s):  
Jie Jack Li ◽  
Chris Limberakis ◽  
Derek A. Pflum
Keyword(s):  
Low Temperature ◽  
Organic Synthesis ◽  
Secondary Alcohol ◽  
Primary Alcohol ◽  
Protecting Groups ◽  
Silyl Ether ◽  
Benzyl Ether ◽  
Protecting Group ◽  
Selective Protection ◽  
Death Taxes

In his book, Protecting Groups, Philip J. Kocieński stated that there are three things that cannot be avoided: death, taxes, and protecting groups. Indeed, protecting groups mask functionality that would otherwise be compromised or interfere with a given reaction, making them a necessity in organic synthesis. In this chapter, for each protecting group showcased, only the most widely used methods for protection and cleavage are shown. Also, this section is not comprehensive and only addresses some of the most common blocking groups in organic synthesis. For a thorough review of protecting groups, the reader should consult the following references: (a) Wuts, P. G. M.; Greene, T. W.; Protective Groups in Organic Synthesis, 4th ed.; Wiley: Hoboken, NJ, 2007; (b) Kocienski, P. J. Protecting Groups, 3rd edition.; Thieme: Stuggart, 2004. In this section, the formation and cleavage of eight protecting groups for alcohols and phenols are presented: acetate; acetonides for diols; benzyl ether; para-methoxybenzyl (PMB) ether; methyl ether; methoxymethylene (MOM) ether; tert-butyldiphenylsilyl (TBDPS) silyl ether; and tetrahydropyran (THP). Acetate is a convenient protecting group for alcohols—easy on and easy off. Selective protection of a primary alcohol in the presence of a secondary alcohol can be achieved at low temperature. The drawback of this protecting group is its incompatibility with hydrolysis and reductive conditions.

Synthesis and Biological Effects of Acyclic Analogs of Deazapurine Nucleosides

1993 ◽  
Vol 58 (3) ◽  
pp. 629-648 ◽  
Author(s):  
Hana Dvořáková ◽  
Antonín Holý ◽  
Ivan Votruba ◽  
Milena Masojídková
Keyword(s):  
Biological Activity ◽  
Acid Hydrolysis ◽  
Acid Medium ◽  
Biological Effects ◽  
Protecting Groups ◽  
Diethyl Acetal ◽  
Subsequent Removal ◽  
Antiviral Activities ◽  
Cesium Salts

Deaza analogs of three basic types of S-adenosyl-L-homocysteine hydrolase (SAHase) inhibitors, (S)-DHPA (I), eritadenine (II) and AHPA (III), were prepared. Alkylation of 3-deazaadenine (V), 3-deazapurine (VI), 1-deazaadenine (VII) and 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine (XXII) with (R)-2,2-dimethyl-4-tosyloxymethyl-1,3-dioxolane (XIIIb), followed by acid hydrolysis, afforded the corresponding (S)-2,3-dihydroxypropyl derivatives XVIIa -XIXa and XXV. Reaction of V and VII with 2,3-O-cyclohexylidene-D-erythrono lactone (XXIX) and subsequent removal of the protecting groups in an acid medium gave eritadenine analogs XXVII and XXVIII. Compounds V and VII were alkylated with bromoacetaldehyde diethyl acetal to give N-(2,2-diethoxyethyl) derivatives XXXII and XXXIII from which the substituted acetaldehyde derivatives were liberated in situ and converted into compounds XXX and XXXI by cyanohydrine reaction followed by acid hydrolysis. The alkylations were performed in dimethylformamide with sodium or cesium salts of the bases. Biological activity was observed only with 3-deazaadenine derivatives XVIIa, XXVII and XXX, which exhibit both enzyme-inhibitory and antiviral activities.

scholarly journals Mukaiyama-Michael vinylogous additions to nitroalkenes under solvent-free conditions

2012 ◽  
Vol 10 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Arrigo Scettri ◽  
Rosaria Villano ◽  
Patrizia Manzo ◽  
Maria Acocella
Keyword(s):  
Good Yield ◽  
Conjugate Addition ◽  
Solvent Free ◽  
Silyl Ether ◽  
Bronsted Acids ◽  
Solvent Free Conditions

AbstractThe first Mukaiyama-Michael vinylogous reaction of a dioxinone-derived silyl ether to nitroalkenes is reported. The conjugate addition is performed in absence of any catalyst under solvent-free conditions, proceeding with satisfactory efficiency with variously substituted nitroalkenes.Moreover, the first organocatalyzed Mukaiyama-Michael vinylogous reaction of trimethylsilyloxyfuran to nitroalkenes is described.The reaction is promoted by Brønsted acids under solvent-free conditions, taking place in moderate to good yield with variously substituted nitroalkenes..

Synthetic Versatility of Lipases: Application for Si–O Bond Formation and Cleavage

Synthesis ◽  
2018 ◽  
Vol 51 (02) ◽  
pp. 477-485 ◽  
Author(s):  
Patrícia Brondani ◽  
Mateus Mittersteiner ◽  
Morgana Voigt ◽  
Bruna Klinkowski ◽  
Dilamara Riva Scharf ◽  
...  
Keyword(s):  
Room Temperature ◽  
Bond Formation ◽  
Inert Atmosphere ◽  
Protecting Groups ◽  
Silyl Ether ◽  
Secondary Alcohols ◽  
Protecting Group ◽  
Silyl Ethers ◽  
Dry Conditions ◽  
Silicon Based

Several commercially available lipases were examined in a study on O–Si bond formation and cleavage applying silicon-based protecting groups and alcohols or the corresponding silyl ethers. With regard to deprotection, from silyl ether to the corresponding alcohol, only the solvent and the lipase were necessary. The influence of the protecting group, the lipase source, and the substituent was investigated to optimize the results. The TMS moiety could be removed in 24 hours of reaction at room temperature in aqueous systems (conv. up to 99%, depending on the substrate and lipase). The reverse reactions, that is, with the protection of the alcohols, were carried out in hexane using different silyl chlorides. The TMS, TES, and TBS moieties were successfully inserted in the primary and secondary alcohols without the need for dry conditions or an inert atmosphere, presenting conversions of up to 99%, depending on the substrate.

The Synthesis of Membrane Permeant Derivatives of myo-Inositol 1,4,5-Trisphosphate

2006 ◽  
Vol 59 (12) ◽  
pp. 887 ◽  
Author(s):  
Stuart J. Conway ◽  
Jan W. Thuring ◽  
Sylvain Andreu ◽  
Brynn T. Kvinlaug ◽  
H. Llewelyn Roderick ◽  
...  
Keyword(s):  
Second Messenger ◽  
Protecting Groups ◽  
Subsequent Removal ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Enzymes ◽  
Derivatives Of

In order to enable the study of the intracellular second messenger d-myo-inositol 1,4,5-trisphosphate (InsP3) and its receptors (InsP3Rs), it has been desirable to develop protected derivatives of InsP3 that are able to enter the cell, upon extracellular application. The subsequent removal of the lipophilic protecting groups, by intracellular enzymes, releases InsP3 and leads to the activation of InsP3Rs. Two syntheses of d-myo-inositol 1,4,5-trisphosphate hexakis(butyryloxymethyl) ester (d-InsP3/BM) and one of l-InsP3/BM are reported. It is demonstrated that extracellular application of the d-enantiomer results in Ca2+ release, which is thought to occur via InsP3Rs. Application of the l-enantiomer resulted in little Ca2+ release.

scholarly journals Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

2020 ◽  
Vol 16 ◽  
pp. 106-110 ◽  
Author(s):  
Tapasi Manna ◽  
Arin Gucchait ◽  
Anup Kumar Misra
Keyword(s):  
Cell Wall ◽  
Perchloric Acid ◽  
Good Yield ◽  
Protecting Groups ◽  
O Antigen ◽  
Synthetic Strategy ◽  
Convenient Synthesis ◽  
Selection Of ◽  
Glycosyl Donors

A straightforward sequential synthetic strategy has been developed for the synthesis of a pentasaccharide repeating unit corresponding to the cell wall O-antigen of the Escherichia albertii O4 strain in very good yield with the desired configuration at the glycosidic linkages using thioglycosides and trichloroacetimidate derivatives as glycosyl donors and perchloric acid supported over silica (HClO4/SiO2) as a solid supported protic acid glycosyl activator. The expected configuration at the glycosidic linkages was achieved using a reasonable selection of protecting groups in the manosaccharide intermediates.

Moulting hormones of insects and crustaceans: The synthesis of 22-deoxycrustecdysone

1969 ◽  
Vol 22 (7) ◽  
pp. 1517 ◽  
Author(s):  
MN Galbraith ◽  
DHS Horn ◽  
EJ Middleton ◽  
RJ Hackney
Keyword(s):  
Spectral Properties ◽  
Grignard Reagent ◽  
Chromic Acid ◽  
Protecting Groups ◽  
Acid Oxidation ◽  
Silyl Ether ◽  
Partial Synthesis ◽  
Chromic Acid Oxidation ◽  
Hydrolysis Of ◽  
Moulting Hormones

A partial synthesis of the title compound (III) has been accomplished from crustecdysone (I). Chromic acid oxidation of crustecdysone afforded the ketone (VI) which was converted into the corresponding acetonide silyl ether (IX). Alkylation of (IX) with the Grignard reagent from (XI) and hydrolysis of the protecting groups afforded the required compound (III). An alternative route which facilitates tritium labelling afforded the same product. The biological activity and spectral properties of the product are discussed.

Enzymatic resolution of γ-carboxy-DL-glutamic acid

1984 ◽  
Vol 49 (11) ◽  
pp. 2562-2565 ◽  
Author(s):  
Václav Čeřovský ◽  
Karel Jošt
Keyword(s):  
Glutamic Acid ◽  
Optically Active ◽  
Protecting Groups ◽  
Subsequent Removal ◽  
Enzymatic Resolution ◽  
Enantioselective Reaction

Optically active γ-carboxy-L-glutamic acid was prepared by enantioselective reaction of benzyloxycarbonyl-γ-carboxy-DL-glutamic acid with phenylhydrazine, catalyzed by papain (E.C.3.4.22.2), and subsequent removal of the protecting groups from the obtained benzyloxycarbonyl-γ-carboxy-L-glutamic acid α-phenylhydrazide.

Pyrrole chemistry. XIX. Reactions of 2-pyrrolecarbonitrile and its 4-substituted derivatives

1978 ◽  
Vol 56 (5) ◽  
pp. 654-657 ◽  
Author(s):  
Hugh J. Anderson ◽  
Cyril R. Riche ◽  
Thomas G. Costello ◽  
Charles E. Loader ◽  
Graham H. Barnett
Keyword(s):  
Good Yield ◽  
Aldehyde Group ◽  
Subsequent Removal ◽  
Substituted Pyrroles

2-Pyrrolecarbonitrile has been acylated to its 4-formyl, trichloroacetyl, ester, and thiolester derivatives. Further reactions gave other 2,4-difunctionalized compounds. These included conversion of the 2-nitriles to the corresponding 2-aldehydes. Subsequent removal of the aldehyde group afforded several 3-substituted pyrroles in good yield.

Deoxygenation of diarylmethanols with dilute mineral acid

2010 ◽  
Vol 88 (10) ◽  
pp. 1003-1008 ◽  
Author(s):  
Kyle A. Hope-Ross ◽  
John F. Kadla
Keyword(s):  
Hydrochloric Acid ◽  
Efficient Method ◽  
Mineral Acid ◽  
Protecting Groups ◽  
Silyl Ether ◽  
One Pot ◽  
Alternative Procedures ◽  
Reaction Works

A new mild and efficient method for the deoxygenation of diarylmethanols is reported. The reaction employs catalytic hydrochloric acid in ethanol at reflux for 48 h. This reaction works on a variety of diarylmethanol substrates and mitigates the need for expensive and toxic reagents such stannanes and silanes used in alternative procedures. In addition, this reaction can be used in tandem with the deprotection of acid-sensitive silyl ether protecting groups in a one-pot procedure.

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