1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides with a Cellulose-Derived Chiral Enone. A Novel Route for Organocatalysts Development

A. M. SAROTTI; R. A. SPANEVELLO; A. G. SUÁREZ; G. A. ECHEVERRÍA; O. E. PIRO

ORGANIC LETTERS

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 14 p. 2556 - 2559

1523-7060

The synthesis of new chiral organic templates starting fromrenewable feedstocks is of enormous value in modern organic synthesis. As a result, intensive research activity has been pursued worldwide to identify attractive chemical transformations to convert biomass into highly valuable organic chemicals. Levoglucosenone (1,6-anhydro-3,4-dideoxy-â-D-glycero-hex-3-enopyranos-2-ulose) (1) is a versatile and easily available chiral building block from the carbohydrate family.2 Conventional pyrolysis of cellulose-containing materials such as waste paper is typically used to generate 1, but microwave irradiation of microcrystalline cellulose was recently found to be an effective alternative. As part of our ongoing interest in the development of new tools for asymmetric synthesis using levoglucosenone derivatives,4 we envisaged the use of 1 in the preparation of novel enantiomerically pure poly substituted pyrrolidines, molecular scaffolds that are found in many efficient chiral organocatalysts. Since 1 has a unique dipolarophilic reactivity, as was established with dipoles such as nitrones and nitrile oxides,6 we foresaw the 1,3-dipolar cycloaddition cycloaddition (1,3-DPC) using azomethine ylides(AMY) as a direct route to achieve our goals.Levoglucosenone (1,6-anhydro-3,4-dideoxy-â-D-glycero-hex-3-enopyranos-2-ulose) (1) is a versatile and easily available chiral building block from the carbohydrate family.2 Conventional pyrolysis of cellulose-containing materials such as waste paper is typically used to generate 1, but microwave irradiation of microcrystalline cellulose was recently found to be an effective alternative. As part of our ongoing interest in the development of new tools for asymmetric synthesis using levoglucosenone derivatives,4 we envisaged the use of 1 in the preparation of novel enantiomerically pure poly substituted pyrrolidines, molecular scaffolds that are found in many efficient chiral organocatalysts. Since 1 has a unique dipolarophilic reactivity, as was established with dipoles such as nitrones and nitrile oxides,6 we foresaw the 1,3-dipolar cycloaddition cycloaddition (1,3-DPC) using azomethine ylides(AMY) as a direct route to achieve our goals.