Regioselective de-O-benzylation of phenylsulfonylethylidene (PSE) acetals-containing benzylated monosaccharides using triisobutylaluminum (TIBAL)

Active Cobalt Catalyst for the Cleavage of Benzyl Ether

“…Among the many protective groups, benzyl ether is one of the most often used protecting groups because of its easy formation, inherent stability, and mild cleavage conditions. 1 A plethora of reagents and methods have been used to remove benzyl ethers, including catalytic hydrogenolysis, 2−6 reductive cleavage (lithium naphthalenide 7,8 and TIBAL, 9 etc. 10,11 ), Lewis acid (TMSI 12 and TiCl 4 , 13 etc.…”

Dramatic effect of PSE clamping on the behaviour of d-glucal under Ferrier I conditions

“…2 In addition, they display a remarkable stability under oxidative conditions (DDQ) 3 or in the presence of strong Lewis acids. 4 Considering the stability of the PSE acetal moiety under various acidic conditions, we turned our attention onto one of the most classical carbohydrate transformations: the allylic rearrangement of acylated glycals known as the Ferrier I reaction. 5 This involves the introduction under Lewis acid conditions of a nucleophilic group at the C-1 of a glycal with simultaneous shifting of the double bond between C-2 and C-3.…”

Systematic Study of Regioselective Reductive Ring-Opening Reactions of 4,6-O-Halobenzylidene Acetals of Glucopyranosides

“…The expected 4-O-ether derivative 4c was isolated with 51% yield, and the two byproducts obtained (9, 11%; 10, 9%) were identified as partial debenzylated derivatives of the major product. Chelationcontrolled selective de-O-benzylation of polybenzylated carbohydrates with Lewis acids 31 including triisobutylaluminum (TIBAL) 32 and diisobutylaluminum hydride (DIBAL-H) 33 is well-documented. According to these literature results, the formation of 9 can proceed via the pentacoordinated Al complex I-9 (Scheme 4).…”