Photooxygenation of alditol-1-C-yl derivatives of furan with singlet oxygen

Sanz, JoséManuel Bánez; González, Diego Galisteo; Sastre, Juan Antonio López; Amo, J. F. Rodriguez; García, Cristina Romero-Ávila; Santos, Mercedes; Sanz‐Tejedor, M. Ascension

doi:10.1016/0008-6215(96)00117-6

Cited by 6 publications

(2 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, to the best of our knowledge, carbohydrates have not served as chiral auxiliaries for the stereoselective transfer of 1 O2 until now. Only sugarfurans have been photooxygenated, but the intermediary formed peroxides rearrange thermally and cannot be isolated [28][29][30]. Based on our experience in carbohydrate chemistry [31][32][33] and acene oxidations [34][35][36][37], we became interested in a combination of both research topics and in sugar-substituted naphthalenes 1 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stereoselective [4+2] Cycloaddition of Singlet Oxygen to Naphthalenes Controlled by Carbohydrates

2021

View full text Add to dashboard Cite

Stereoselective reactions of singlet oxygen are of current interest. Since enantioselective photooxygenations have not been realized efficiently, auxiliary control is an attractive alternative. However, the obtained peroxides are often too labile for isolation or further transformations into enantiomerically pure products. Herein, we describe the oxidation of naphthalenes by singlet oxygen, where the face selectivity is controlled by carbohydrates for the first time. The synthesis of the precursors is easily achieved starting from naphthoquinone and a protected glucose derivative in only two steps. Photooxygenations proceed smoothly at low temperature, and we detected the corresponding endoperoxides as sole products by NMR. They are labile and can thermally react back to the parent naphthalenes and singlet oxygen. However, we could isolate and characterize two enantiomerically pure peroxides, which are sufficiently stable at room temperature. An interesting influence of substituents on the stereoselectivities of the photooxygenations has been found, ranging from 51:49 to up to 91:9 dr (diastereomeric ratio). We explain this by a hindered rotation of the carbohydrate substituents, substantiated by a combination of NOESY measurements and theoretical calculations. Finally, we could transfer the chiral information from a pure endoperoxide to an epoxide, which was isolated after cleavage of the sugar chiral auxiliary in enantiomerically pure form.

show abstract

Section: Introductionmentioning

confidence: 99%

“…However, to the best of our knowledge, carbohydrates have not served as chiral auxiliaries for the stereoselective transfer of 1 O 2 until now. Only sugar-furans have been photooxygenated, but the intermediary formed peroxides rearrange thermally and cannot be isolated [ 28 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%