Acetonide Deprotection Research Articles

Total synthesis of (−)-cleistenolide

The total synthesis of (−)-cleistenolide, a novel natural product recently isolated from the annonaceae species cleistochlamys kirkii oliver, is described. The synthesis proceeds starting from easily accessible d-manitol using a selective benzoylation, a selective acetonide deprotection, silylprotection and ring-closing metathesis reaction.

Stereoselective first total synthesis, confirmation of the absolute configuration and bioevaluation of botryolide-E

A simple, first stereoselective total synthesis of botryolide-E has been described. The synthesis started from propylene oxide employing Jacobsen's hydrolytic kinetic resolution (HKR), selective epoxide opening, sharpless asymmetric dihydroxylation, one pot acetonide deprotection and lactonization as key steps. Further, the synthesis confirms the absolute configuration of the natural product botryolide-E and we evaluated the biological behavior of natural product botryolide-E against a panel of bacteria and fungi. Botryolide-E exhibits significant potent activity against Staphylococcus aureus (MTCC 96) (6.25 μg/ml), good against Escherichia coli (MTCC 443) (12.5 μg/ml), Bacillus subtilis (MTCC 441) (25 μg/ml) and compound 1 exhibited good to moderate antifungal activity.

ChemInform Abstract: Mild, Versatile, and Chemoselective Indium(III) Triflate‐Catalyzed Deprotection of Acetonides under Microwave Heating Conditions.

AbstractThe method allows the presence of acid‐labile functional groups.

Mild, versatile, and chemoselective indium(III) triflate-catalyzed deprotection of acetonides under microwave heating conditions

A series of acetonides (both terminal and internal isopropylidene acetals) have been deprotected under catalytic, neutral conditions to give their corresponding 1,2-diols. The reactions utilize indium(III) triflate in the presence of water and an organic solvent with mild microwave heating. Terminal acetonides are chemoselectivley removed in the presence of internal acetonides; acid labile functional groups remain intact under these conditions, thereby greatly enhancing the scope of the reaction substrates that can be utilized with this approach.

A Synthetic Route to Fully Substituted Chiral Cyclopentylamine Derivatives: Precursors of Carbanucleosides

Removal of silyl protection from D-glucose derived substrate 6 afforded 7, which upon acetonide deprotection followed by reaction with N-benzylhydroxylamine furnished two isomeric isoxazolidinocyclopentane derivatives via spontaneous cyclization of an in situ generated nitrone. The methyl xanthate derivative of the tertiary hydroxyl group of one isomer was isolated and subjected to radical deoxygenation reaction to form epimeric products, while with the other isomer it underwent spontaneous 1,2-elimination to form a mixture of the two possible endocyclic olefins. Hydrogenolytic cleavage of the isoxazolidine rings of the purified products followed by insertion of 5-amino-4-chloropyrimidine moiety and purine ring construction smoothly afforded structurally unique carbanucleoside analogues. Various spectroscopic methods on the synthesized compounds and X-ray analysis on one important intermediate were used to assign the structures and stereochemistry of the products.

Synthesis of Glycocinnasperimicin†D

The first total synthesis of amino sugar antibiotic glycocinnasperimicin D (1) has been achieved by a convergent, three-component coupling strategy. The key steps involve the Heck-Mizoroki reaction by using the iodophenyl glycoside 50 and acryl amide 32 to furnish the right core structure of 1, and the construction of the urea glycoside employing the reaction of glycosyl isocyanate 8 with amino sugar 9. Glycosyl isocyanate 8 was prepared by the oxidation of isonitrile 10, which displayed excellent reactivity in the coupling event. Synthetic roadblocks, encountered during this synthetic effort, have led to the development of the alpha-selective, Lewis acid catalyzed phenyl glycosylation process with 2-amino-hexopyranose and a procedure for acetonide deprotection without affecting the silyl ethers.

Indium Trichloride Mediated Cleavage of Acetonides in the Presence of Acid-Labile Functional Groups - Enhancing the Synthetic Utility of 1,3-Dioxolanyl-Substituted 1,2-Oxazines

Indium trichloride in an acetonitrile-water mixture chemoselectively cleaved the isopropylidene acetals of various 1,3-dioxolanyl-substituted 1,2-oxazines as well as carbohydrate derivatives. Deprotection of acetonides can be achieved in substrates susceptible for acid-induced cyclizations. Most importantly, enol ether moieties are not attacked and the presence of glycosidic linkages or acid-sensitive protecting groups such as tert-butyldimethylsilyl, 2-(trimethylsilyl)ethyl, or tert-butoxycarbonyl is also tolerated.

Trimethylsilyl Trifluoromethanesulfonate (TMSOTf) Assisted Facile Deprotection of N,O-Acetonides

Employing TMSOTf as an easily available reagent, we have developed a mild and efficient method for the deprotection of both terminal and internal N,0-acetonide functionalities. Various regularly used protecting groups and common organic functional moieties were found to be unaffected by the described reaction conditions. In a few representative examples, the present method was also extended to deprotect acetonides obtained from 1,2-, and 1,3-terminal diols. The acetonide deprotection protocol described herein is expected to be a useful addition to the presently available methods for performing the above transformation.

A novel method for the protection of amino alcohols and carbonyl compounds over a heterogeneous, reusable catalyst

Abstract A novel application of Al-SBA-15 catalyst in the protection of amino alcohols and carbonyl compounds is reported. N-t-butoxy carbonyl [N(Boc)] amino alcohols were protected using 2,2-dimethoxypropane (DMP) to form acetonides. Acetonide deprotection was also studied using the same catalyst to obtain the parent amino alcohol. Protection of carbonyl compounds was studied using neopentyl glycol, ethylene glycol and propylene glycol as the protecting agents. A series of commercially important molecules such as 2-substituted and 2,2-disubstituted 1,3-benzodioxoles were synthesized by reacting carbonyl compounds with catechol.

Stereoselective Total Synthesis of (+)-Goniothalesdiol and (+)-2,5-epi-­Goniothalesdiol from d-Mannitol

An efficient and practical total synthesis of (+)-gonio-thalesdiol and its 2,5- EPI analogue is described herein. The key -features include a diastereoselective reduction of C-5 keto with Zn(BH 4 ) 2 to generate the desired stereochemistry at C-5. The tetra-hydrofuran backbone of natural goniothalesdiol was synthesized under basic conditions via epoxide formation, followed by in situ 5- EXO opening of the epoxide ring with γ-benzoyloxy oxygen upon -debenzoylation. For the 2,5- EPI analogue, the tetrahydrofuran ring was formed via acid-catalyzed acetonide deprotection followed by concomitant S N 2 displacement of the O-mesyl group at C-5 center with C-2-γ-oxygen.

A Mild and Efficient Method for the Chemoselective Deprotection of Acetonides with Lanthanum(III) Nitrate Hexahydrate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chemoselective hydrolysis of terminal isopropylidene acetals in acetonitrile using molecular iodine as a mild and efficient catalyst

A simple, mild and efficient method for deprotection of acetonides in the presence of molecular iodine is described. Acid labile protecting groups such as PMB, OMe, OBn, allyl and propargyl are compatible with the reaction conditions, while TBS, TBDPS, TMS and THP ethers were unstable under the same conditions.

A mild and efficient method for the chemoselective deprotection of acetonides with lanthanum(III) nitrate hexahydrate

Acetonides are hydrolyzed selectively and efficiently with lanthanum(III) nitrate hexahydrate in acetonitrile. The method has good compatibility with other sensitive hydroxyl protecting groups such as trityl, TBDMS, THP, OAc, OBz and OBn.

Polymer‐Supported Ferric Chloride as a Heterogeneous Catalyst for Chemoselective Deprotection of Acetonides.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Vanadium(III) chloride: A mild and efficient catalyst for the chemoselective deprotection of acetonides

Acetonides are selectively cleaved at room temperature by a catalytic amount of VCl 3 in methanol to furnish the corresponding diols under mild conditions. Other hydroxyl protecting groups such as TBDMS, TBDPS, Ac, THP, Bn, prenyl, allyl present in the substrate were intact under the reaction conditions.

Polymer-Supported Ferric Chloride as a Heterogeneous Catalyst for Chemoselective Deprotection of Acetonides

Acetonides undergo chemoselective deprotection to afford the corresponding 1,2-diols in excellent yields using polymer (PVP)-supported ferric chloride as a heterogeneous catalyst in acetonitrile-dichloromethane at room temperature.

Mild and Facile Procedure for Clay‐Catalyzed Acetonide Protection and Deprotection of N(Boc)‐Amino Alcohols and Protection of 1,2‐Diols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Mild and facile procedure for clay-catalyzed acetonide protection and deprotection of N(Boc)-amino alcohols and protection of 1,2-diols

The application of clay as a catalyst for acetonide protection of N(Boc)-amino alcohols and 1,2-diols to obtain good to excellent yields of the acetonide derivatives is described. Acetonide deprotection to obtain the parent amino alcohol was carried out using a similar catalyst in the presence of methanol as solvent. The reaction takes place at room temperature within 2h to give the parent amino alcohol in quantitative yield keeping the N(Boc) group intact.

A Simple and Facile Chemo‐ and Regioselective Deprotection of Acetonides Using Silica Supported Sodium Hydrogen Sulfate as a Heterogeneous Catalyst.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Simple and Facile Chemo- and Regioselective Deprotection of Acetonides Using Silica Supported Sodium Hydrogen Sulfate as a Heterogeneous Catalyst

Abstract Silica supported sodium hydrogen sulfate (NaHSO4·SiO2) has been found to be an efficient heterogeneous catalyst for chemo- and regioselective deprotection of acetonides at room temperature to produce the corresponding diols in excellent yields.