One-pot Preparation and Characterisation of Five-membered Cyclic Alcohols

Background: Over the last few years, one of the primary focuses of our research group has been the synthesis and biological evaluation CANs featuring structural and/or configurationally alterations on the carbocyclic moiety. We previously reported an enlarged group of diversely functionalized amino cyclopentenols, cyclopentenols and cyclopentenones as useful precursors in the synthesis and posterior biological evaluation of CANs featuring structural and/or configurationally alterations on the carbocyclic moiety; moreover the five-membered carbocycles are common structural units in other natural products and bioactive compounds, for this reason, these compounds presented great interest for their use as building blocks in the development of compounds with potential pharmacological activities. Method: The conversion of benzyl cyclopent-3-enocarboxylate into a mixture of the corresponding hydroxy allylic esters 5a and 5b was efficiently achieved by the employed diphenyl diselenide, H2O2 in dry CH2Cl2 for the synthesis of phenylselenenic acid and electrophilic addition to double bond of 3, and 90% tert-butyl hydroperoxide subsequently being added. Results: The mixture of compounds 5 was obtained in good yields under these conditions, and this was readily separated by column chromatography. Isolated components were identified by 1H and 13C NMR spectral, as well as by its EI HRMS. The corresponding alcohols 5a or 5b were easily transformed in the corresponding 3,5-dinitrobenzoyl derivatives, 6a and 6b, from which single crystals were obtained, permitting unequivocal identification. Conclusion: Using a one-pot method, benzyl cyclopent-3-enecarboxylate was turned into a mixture of corresponding hydroxy allylic derivatives 5a and 5b, employing diphenyl diselenide, H2O2 and tertbutyl hydroperoxide for the formation and subsequent oxidation/elimination of the first-generated alkyl phenyl selenides. The use of these oxidants corresponds to modern trends in organic synthesis, because they are easily available and environmentally friendly reagents, which can be used at a large scale.