Synthesis of 5-deoxy-d-Galactofuranosides (5-deoxy-l-arabino-Hexofuranosides) starting from D-Galacturonic acid by Photoinduced Electron Transfer (PET) Deoxygenation

MARINO, CARLA; BORDONI, A; LO FIEGO, MARCOS; MUCHNIK DE LEDERKREMER, ROSA

Carbohydrate Chemistry: Proven Synthetic Methods 3

TAYLOR & FRANCIS INC

Año: 2014;

The development of specific deoxygenation methods for carbohydrates is important as deoxy sugars are useful not only for enzymatic characterization, but also for the synthesis of natural products from carbohydrate precursors as chiral templates.1-3 Since its development in 1975, the Barton-McCombie deoxygenation method has been extensively employed.4 However, this procedure involves the use of organotin compounds, which are toxic, expensive and difficult to remove. Thus, many modifications were later developed using other hydride donors.5 Photochemical reactions are attractive in the modern context of green chemistry as they often occur with few reagents and the formation of byproducts is also minimized. In the frame of our project dedicated to the characterization of D-galactofuranosidases it was very useful the photoinduced electron-transfer (PET) reduction of hydroxyl groups derivatized as 3-(trifluormethyl)benzoyl esters, using 9-methylcarbazole (MCZ) as photosensitizer. This reaction was first used by Rizzo et al. for the synthesis of deoxyribonuleosides (A, Scheme 1).7 We investigated the PET deoxygenation on D-galactono-1,4-lactone (B), D-galacturonic acid (C) and D-glucofuranosidurono-6,3-lactone (D) derivatives.