Synthesis of novel bicyclic prostaglandins by photochemical cycloaddition reactions

Abstract

Light-induced addition reactions of cyclopentenone derivatives with ethylene, followed by elaboration of the alkyl chains a t positions 8 and 12, give bicyclic prostanoic acid analogues belonging to the prostaglandin E, and Fza series. Cycloaddition of ethylene to prostaglandin A2 methyl ester yields simultaneously the IX-and p-cycloadducts. Photochemical addition of allene to prostaglandin A, derivatives affords mixtures of photoadducts which vary with the nature of the functional group a t position 15, thus illustrating the versatility of these photocondensation reactions.

Expedient Synthesis of C‐Aryl Carbohydrates by Consecutive Biocatalytic Benzoin and Aldol Reactions

“…The relative stereochemistry was assessed by NMR spectroscopy upon formation of the corresponding 1,3‐dioxolan‐2‐one derivatives (see Tables S8 and S9 as well as Figures S9 and S10 in the Supporting Information for products S5 a and S6 a ). [b] Prepared from ZnCl 2 and NaBH 4 in THF 21. [c] No reaction observed.…”

Synthesis of the Demospongic Compounds, (6Z, 11Z)-Octadecadienoic Acid and (6Z, 11Z)-Eicosadienoic Acid

“…Its Z-selective Wittig olefination [10] with the known phosphor-ane generated from 6 [11] furnished compound 7. Although Wittig reactions with carboxylic acids bearing phosphoranes are reported in the literature [12], we encountered difficulty in the isolation step leading to poor yield of the Wittig product.…”

High‐Speed Reduction of Triarylpyrylium Salts Using Zn(BH4)2/SiO2 as an Efficient and Regiospecific Reducing Reagent

“…e selectivity is generally achieved by the use of modi�ed reducing reagents which are formed by the replacement of hydride with sterically bulky substituents or electronwithdrawing groups [1][2][3][4]. us to achieve this goal, currently the use of modi�ed hydride donors has been expanded [5][6][7][8].…”