Desulfonyloxylations of some secondary p-toluenesulfonates of glycosides by lithium triethylborohydride; a high-yielding route to 2- and 3-deoxy sugars

A One-Pot Method for Removal of Thioacetyl Group via Desulfurization under Ultraviolet Light To Synthesize Deoxyglycosides

“…The synthesis of deoxy sugars, especially the synthesis of 2-deoxyglycosides and their derivatives, has drawn increasing attention from carbohydrate chemists because many bioactive natural products have deoxyglycosides as the main constituents of glycosidic chains that play significant roles in bioactivity. − Usually, these deoxy carbohydrate derivatives were synthesized through the reduction of glycals, glyco-epoxides, glycosides with halides, − and glycosides with a thiocarbonyl group − and thioacetate group. , Recently, we have developed a method to obtain the deoxyglycosides through desulfurization of glycoside thiols under ultraviolet light (Scheme a) in order to overcome the shortcomings of Raney nickel catalyzed reduction of a thioacetate group. , In this method, the acylated substrates have to be deprotected in the first step to form glycosyl thiols, which is then desulfurized in the second step to form unprotected deoxy glycosides. This method may be limited in many applications in which acylated deoxyglycoside derivatives are key intermediates (Scheme b). − ,, Therefore, we wondered if we could develop a method for removal of a thioacetyl group via desulfurization under UV light to obtain acylated deoxyglycoside derivatives.…”

Synthesis of Deoxyglycosides by Desulfurization under UV Light

“…Deoxyglycosides are frequently the main constituents of glycosidic chains in many biologically active natural products, including antibiotics and cardiac glycosides, in which they are thought to play significant roles in bioactivity. − Consequently, the synthesis of deoxysugars and further synthesis of related natural products, particularly 2-deoxyglycosides and their derivatives, has been identified as an important and challenging area of carbohydrate chemistry. − Several deoxysugar production methods have been reported, including the reduction of glycals, glycoepoxides, and glycosides with halides − and thiocarbonyl groups, − all of which have their respective advantages and shortcomings (Scheme a). Hydrogenolytic desulfurization, catalyzed by either Raney nickel or Pd/Al 2 O 3 , was first used to synthesize unprotected peptide segments via native chemical ligation. − Later, a desulfurization method involving tris­(2-carboxyethyl)­phosphine (TCEP) and a radical initiator was developed to overcome the shortcomings of the Raney nickel or palladium method. , …”

Stereoselective Deoxygenation of myo-Inositol Monotosylates with Lithium Triethylborohydride

“…The hydrogen on the carbon with the hydroxyl group undergoes a [1,2] shift to displace the tosylate group with the probable formation of a ketone intermediate that is quickly reduced by LTBH back to a hydroxyl. This mechanism is less sensitive to steric hinderance and it has been utilised to deoxygenate the 2‘ position of adenosine 10 and some hexose sugars …”