Synthetic Studies Towards Bridgehead Diprenyl‐Substituted Bicyclo[3.3.1]nonane‐2,9‐diones as Models for Polyprenylated Acylphloroglucinol Construction

Abstract

The synthesis of bridgehead diprenylated bicyclo[3.3.1]nonane‐2,9‐dione, based on a reductive rearrangement of an enol lactone, is presented. The same target could be reached by a one‐step sequence involving Michael addition of 2,6‐diprenylcyclohexanone onto acrolein and intramolecular aldol reaction. The first method could be extended to the formation of a compound with gem‐dimethyl substituents adjacent to the bridgehead position, but the construction of a suitably substituted enol lactone, with a view to polyprenylated acylphloroglucinol elaboration, could not be achieved. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Domino Michael-aldol annulations for the stereocontrolled synthesis of bicyclo[3.3.1]nonane and bicyclo[3.2.1]octane derivatives

“…Michael-Aldol annulations have furnished polysubstituted cyclohexanone derivatives, in some cases with high enantioselectivity. [19] However, with few exceptions, [20] a cyclohexanone ring lacking an electron-withdrawing group at the α-position has seldom been shown to react with an enone or enal to give a bicyclo ketol. Bicyclo formation has mainly been achieved by reacting α-alkoxycarbonyl-or α-acyl-cycloalkanones with either aldehydes [21][22][23] or ketones.…”

Synthesis of a D Ring‐Functionalized Derivative of the Epiwelwistatin Tetracyclic Core

“…Because of the possibility of converting 2‐bromoindoles into oxindoles under hydrolytic conditions, we first examined the halogenation of compound 15 under a number of conditions, but many of these resulted in complex mixtures. The reaction with phenyltrimethylammonium tribromide25 proceeded cleanly. Depending on the amount of brominating agent, this reaction afforded either compound 17 , from bromination α to the carbonyl group on the D ring, or 18 , from a double bromination reaction.…”

Polyprenylated Phloroglucinols and Xanthones

“…New approaches have appeared in the literature, aimed at a facile method for the construction of the bicyclic core of PPAPs that will allow easier access to those compounds for their biological evaluation and SAR studies [55][56][57][58][59][60][61].…”