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Identifier

000346047

Title

Σύνθεση σπειροκεταλικών και 3-κετοτετραϋδροφουρανικών σκελετών φυσικών προϊόντων στη βάση της χημείας του μοριακού οξυγόνου

Alternative Title

Synthesis of spiroketal and 3-ketotetrahydrofuran motifs from natural products using singlet oxygen

Author

Τοφή, Μαρία Κ

Thesis advisor

Βασιλικογιαννάκης, Γεώργιος

Abstract

The synthesis of the [6,6,5]-bispiroketal skeleton of the natural product salinomycin is described in this thesis. A cascade sequence initiated by a [4+2]-cycloaddition of singlet oxygen (1O2) to a furylic ketone followed by two sequential cyclizations and a ketalization step is at the heart of this process. The synthesis of the AB spiroketals, as well, as the C-ring, of the natural products pectenotoxins (PTXs) is also described. The key step for the synthesis of the AB spiroketals includes a [4+2]-cycloaddition of 1O2 to a 2,5-disubstituted furan followed by intramolecular nucleophilic opening of the intermediate endoperoxide. OOOOOOHMeOHOR1XR2YBAOOOMeOHMeOHOOMeOR2BOOOMeAskeleton of SalinomycinX= OHY= HR1= MeX, Y = HR2 = OHR1 =R1 =X, R2 = HY = OH3-keto-tetrahydrofuranskeleton of Pectenotoxins 8-10skeleton of Pectenotoxins 1-7R2 = X, R1 = HY = OH1O2665 The construction of the C-ring of PTXs was achieved via an oxo-Michael addition of a free hydroxyl functionality to the α,β-unsaturated system of a 1,4-enedione, derived by photooxidation of a 2-(β-hydroxyalkyl) furan. On the same basis, a general, fast and high yielding synthetic methodology for the synthesis of 3-keto-tetrahydrofurans via photooxidation of easily synthesized 2-(β-hydroxyalkyl) furans was developed. The key step of the developed methodology sees five distinct transformations achieved during a single synthetic operation.

Language

Greek

Subject

3-Keto-tetrahydrofurans

3-Κετο-τετραϋδροφουράνια

Pectenotoxins

Salinomycin

Singlet Oxygen

Spiroketals

[4+2] Cycloaddition

[4+2] Κυκλοπροσθήκη

oxo-Michael Addition