Synthesis of Cyclopentitols by Ring-Closing Approaches

A Boron Alkylidene–Alkene Cycloaddition Reaction: Application to the Synthesis of Aphanamal

“…Considering the prevalence of cyclopentane-containing natural products (> 49 000 according to the Reaxys database), it was of interest to study this cycloaddition in the construction of natural product targets. [18] In this context, we addressed the natural product aphanamal, ab icyclict erpene isolated from the folk medicine plant Chromolaena laevigata. [19,20] As depicted in Figure 4, when geminal bis-(boronate) 40 was subjected to deborylative [2+ +2] cycloaddition followed by trapping with Eschenmoser salt, [21] alkyl amine derivative 41 was isolated in good yield and with good levels of stereoinduction.…”

“…[18] In this context, we addressed the natural product aphanamal, a bicyclic terpene isolated from the folk-medicine plant chromolaena laevigata . [19,20] As depicted in Figure 4, when geminal bis(boronate) 40 was subjected to deborylative 2+2 cycloaddition followed by trap with Eschenmoser salt [21] , alkyl amine derivative 41 was isolated in good yield and with good levels of stereoinduction.…”

Methodology for the Construction of the Bicyclo[4.3.0]nonane Core

“…Metathesis as a cyclization tactic has become a notable method for ring forming reactions. The use of Grubbs or Grubbs-Hoveyda catalysts has often been the choice of catalyst used for these reactions, and their involvement in the synthesis of hydrindanes has become documented (see Scheme 23) [72,73]. Bicyclo[2.2.2]octenes are useful substrates for these reactions because they are readily synthesized from Diels-Alder cycloadditions, and can be utilized to give hydrindane scaffolds with a variety of functionalizations.…”

Cascade rearrangement of furylcarbinols with hydroxylamines: practical access to densely functionalized cyclopentane derivatives

“…6 Consequently, the development of new synthetic methodologies to access densely functionalized aminocyclopentanes with improved efficiency, step economy and accessibility of novel chemotypes, remains an important goal for organic chemists. Approaches for the synthesis of functionalized aminocyclopentanes rely primarily on the nitroso Diels-Alder cycloaddition, 7 the intramolecular Henry reaction 8 and methodology such as RCM, 9 [3 + 2] cycloaddition 10 and the cascade rearrangement of furan derivatives. 11 A highly attractive direct route to densely functionalized aminocyclopentanes is through the cascade rearrangement of furylcarbinols, referred to as the aza-Piancatelli reaction.…”