Stereoselective Synthesis of Higher Sugars by Homologation of Carbohydrate-Derived Enals with Nonracemic .gamma.-(Silyloxy) Allylic Stannanes and Substrate-Directed Hydroxylation
摘要:
A strategy is described for the chain extension of carbohydrate derivatives utilizing sequential Horner-Emmons condensation and then reduction-oxidation to prepare the enal homologue VII, which is converted to the corresponding dienyl bis-OTBS derivative IX upon condensation with a gamma-(silyloxy) allylic stannane VI and subsequent silylation. Dihydroxylation of dienes M with OsO4-NMO leads to syn,anti,syn,anti,syn. hexol derivatives X with excellent diastereoselectivity. These hexols undergo selective oxidative cleavage with H5IO6 to yield gamma-lactols XI. The methodology has been used to prepare the octonic lactone 15 from (S,S)-dimethyl tartrate and the undeconic lactone 32 from D-mannitol.
Stereoselective Synthesis of Higher Sugars by Homologation of Carbohydrate-Derived Enals with Nonracemic .gamma.-(Silyloxy) Allylic Stannanes and Substrate-Directed Hydroxylation
摘要:
A strategy is described for the chain extension of carbohydrate derivatives utilizing sequential Horner-Emmons condensation and then reduction-oxidation to prepare the enal homologue VII, which is converted to the corresponding dienyl bis-OTBS derivative IX upon condensation with a gamma-(silyloxy) allylic stannane VI and subsequent silylation. Dihydroxylation of dienes M with OsO4-NMO leads to syn,anti,syn,anti,syn. hexol derivatives X with excellent diastereoselectivity. These hexols undergo selective oxidative cleavage with H5IO6 to yield gamma-lactols XI. The methodology has been used to prepare the octonic lactone 15 from (S,S)-dimethyl tartrate and the undeconic lactone 32 from D-mannitol.
Stereoselective Synthesis of Higher Sugars by Homologation of Carbohydrate-Derived Enals with Nonracemic .gamma.-(Silyloxy) Allylic Stannanes and Substrate-Directed Hydroxylation
作者:James A. Marshall、Serge Beaudoin
DOI:10.1021/jo00101a020
日期:1994.11
A strategy is described for the chain extension of carbohydrate derivatives utilizing sequential Horner-Emmons condensation and then reduction-oxidation to prepare the enal homologue VII, which is converted to the corresponding dienyl bis-OTBS derivative IX upon condensation with a gamma-(silyloxy) allylic stannane VI and subsequent silylation. Dihydroxylation of dienes M with OsO4-NMO leads to syn,anti,syn,anti,syn. hexol derivatives X with excellent diastereoselectivity. These hexols undergo selective oxidative cleavage with H5IO6 to yield gamma-lactols XI. The methodology has been used to prepare the octonic lactone 15 from (S,S)-dimethyl tartrate and the undeconic lactone 32 from D-mannitol.