Generation of Mixed Anhydrides via Oxidative Fragmentation of Tertiary Cyclopropanols with Phenyliodine(III) Dicarboxylates

Oxidative fragmentation of tertiary cyclopropanols with phenyliodine(III) dicarboxylates in aprotic solvents (dichloromethane, chloroform, toluene) produces mixed anhydrides. The fragmentation reaction is especially facile with phenyliodine(III) reagents bearing electron-withdrawing carboxylate ligands (trifluoroacetyl, 2,4,6-trichlorobenzoyl, 3-nitrobenzoyl), and affords 95−98% yields of the corresponding mixed anhydride products. The latter can be straightforwardly applied for the acylation of various nitrogen, oxygen and sulfur-centered nucleophiles (primary and secondary amines, hydroxylamines, primary alcohols, phenols, thiols). Intramolecular acylation yielding macrocyclic lactones can also be performed. The developed transformation has bolstered the synthetic utility of cyclopropanols as pluripotent intermediates in diversity-oriented synthesis of bioactive natural products and their synthetic congeners. For example, it was successfully applied for the last-stage modification of a cyclic peptide to produce a precursor of a known histone deacetylase inhibitor.

Synthesis & antitumor activity of epothilones B and D and their analogs

Epothilone is a newly developed antitumor drug; its antitumor principle is to stop the cell cycle by binding to tubulin in tumor cells, promoting tubulin polymerization, inhibiting depolymerization of microtubules, and ultimately inducing apoptosis. There are many analogs of epothilone, such as epothilone B, epothilone D, ixabepilone, sagopilone, 21-amino-epothilone B and KOS-1584. Herein, the synthesis and antitumor activity of epothilones B and D were summed up. The antitumor activity of epothilone analogs was also compared. Synthesis of epothilone and its analogs is more complex, and choosing the proper synthetic method is very important. Moreover, these compounds have obvious antitumor effect. The epothilone and its analogs will continue to play an important role in the future treatment of tumors.

Stereoselective synthesis of α-methyl and α-alkyl ketones from esters and alkenes via cyclopropanol intermediates

Alkenes bearing a stereocenter in the allylic position were found to undergo Kulinkovich hydroxycyclopropanation with good diastereoselectivity. For the isomerization of the resulting cyclopropanols to diastereomerically enriched α-methyl ketones, a new mild regioselective method has been developed. A sequence of stereoselective cyclopropanation and cyclopropanol ring opening was successfully employed for the construction of the C20 stereocenter in steroids.

The Kulinkovich hydroxycyclopropanation reaction in natural product synthesis

The Kulinkovich cyclopropanation reaction provides a flexible and convenient method for the synthesis of cyclopropanols. Together with the diverse chemistry of the cyclopropanol unit, it offers access to a wide range of functionalised unsaturated and saturated compounds. The successful use in the synthesis of natural compounds is outlined in this perspective.