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1.
Chem Commun (Camb) ; 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38990064

ABSTRACT

An efficient regioselective method to attach thiocyanato groups at the ß-position of enol double bonds in sugar enol ethers using KSCN and potassium persulfate has been developed. The highly regioselective addition of the resulting sugar thiocyanate to electron rich species like terminal alkynes and benzynes under Pd catalysis generated C-2-thio acrylo/aryl nitrile glycals via simultaneous introduction of thio and cyano groups into carbon-carbon triple bonds.

2.
Chem Commun (Camb) ; 59(69): 10448-10451, 2023 Aug 24.
Article in English | MEDLINE | ID: mdl-37555476

ABSTRACT

We have developed a synthesis of 1-3 and 1-1 disaccharides from 2-benzoyl glycal and anomeric thiol and/or hydroxy sugar acceptors under mild conditions at room temperature. The regio and stereo-selectivity of the newly formed inter-glycosidic linkages are dependent on the nature of the glycal donor (D or L) and anomeric acceptor.

3.
Chem Commun (Camb) ; 59(59): 9090-9093, 2023 Jul 20.
Article in English | MEDLINE | ID: mdl-37403569

ABSTRACT

A facile synthesis of C1-C2 interlinked disaccharides is achieved from readily available iodo-glycals and unsubstituted glycals. Ester-protected donors reacted with ether-protected acceptors under Pd-Ag catalysis to access C-disaccharides bearing C-3 vinyl ether, which upon ring opening by Lewis acid furnished pi-extended conjugated orthogonally protected chiral ketones. Benzyl deprotection and reduction of the double bonds resulted in a fully saturated disaccharide stable toward acid hydrolysis.

4.
J Org Chem ; 88(13): 8300-8309, 2023 Jul 07.
Article in English | MEDLINE | ID: mdl-37315232

ABSTRACT

A simple method for the iodination of unsaturated sugars to form sugar vinyl iodides was developed under oxidant-free conditions using NaH/DMF/iodine as a reagent system at ambient temperature. 2-Iodoglycals bearing ester, ether, silicon, and acetonide protection were synthesized in good to excellent yield. 3-Vinyl iodides derived from 1,2:5,6-diacetonide glucofuranose were transformed to C-3 enofuranose and bicyclic 3,4-pyran-fused furanose via Pd-catalyzed C-3 carbonylation and intramolecular Heck reaction, respectively, as the key step.


Subject(s)
Iodides , Iodine , Carbohydrates , Esters
5.
Chem Asian J ; 17(14): e202200350, 2022 Jul 15.
Article in English | MEDLINE | ID: mdl-35485806

ABSTRACT

Transformation of glycals to 2,3-di-substituted-3-dexoy-glycals were achieved by sequential C2 alkenylation of pseudoglycals followed by capture of nucleophiles at C3 position. Anomeric linked N-(glycosyloxy) acetamides group assisted innate C2-H activation of pseudoglycals under palladium catalysis is achieved. The synthesized C2 alkenylated products were further attacked by thio/amino nucleophiles at C3 position under basic conditions in stereo-selective fashion to generate 2,3-branched glycals with the elimination of directing groups and translocation of double bond. Different control experiments were conducted to establish the role of directing groups in C-H functionalization of pseudoglycals and reason for selectivity.


Subject(s)
Acetamides , Palladium , Catalysis , Palladium/chemistry
6.
Org Biomol Chem ; 18(22): 4174-4177, 2020 06 10.
Article in English | MEDLINE | ID: mdl-32441290

ABSTRACT

A new method for the O-arylation of carbohydrates under metal-free conditions using arynes as an aryl source has been developed. This approach works well with mono, di and trihydroxy compounds. Preferential O-arylation takes place at primary over secondary and equatorial over axial. Site-selective O-arylation was achieved with the substrate having trans vicinal diequatorial hydroxyls.

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