The role of the cyclic 2,3-N,O-carbamate protecting group in directing the selectivity of mannosylation reactions of diacetone-D-glucose, promoted by BSP/Tf2O via a-triflate intermediates, has been investigated through a combined computational and experimental approach. DFT calculations were used to locate the transition states leading to the alpha or beta anomers. These data indicate the preferential formation of the beta-adduct with mannosyl donors either equipped with the 4,6-O-benzylidene protection or without it. The synthetic results confirmed this preference, showing in both cases an alpha/beta selectivity of 4:6. This highlights a role for the 2,3-N,O-carbamate in sharp contrast with what described in the case of 2,3-O-carbonate mannosyl donors.
2,3-Carbamate mannosamine glycosyl donors in glycosylation reactions of diacetone-d-glucose. An experimental and theoretical study
Ronchi, Silvia;Confalonieri, Laura;Imperio, Daniela;Compostella, Federica
2021-01-01
Abstract
The role of the cyclic 2,3-N,O-carbamate protecting group in directing the selectivity of mannosylation reactions of diacetone-D-glucose, promoted by BSP/Tf2O via a-triflate intermediates, has been investigated through a combined computational and experimental approach. DFT calculations were used to locate the transition states leading to the alpha or beta anomers. These data indicate the preferential formation of the beta-adduct with mannosyl donors either equipped with the 4,6-O-benzylidene protection or without it. The synthetic results confirmed this preference, showing in both cases an alpha/beta selectivity of 4:6. This highlights a role for the 2,3-N,O-carbamate in sharp contrast with what described in the case of 2,3-O-carbonate mannosyl donors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
