Thermal reactions of cyclopropenone ketals. Application of the cycloaddition reactions of delocalized singlet vinylcarbenes: three-carbon 1,1-/1,3-dipoles. An alternative synthesis of deacetamidocolchiceine: formal total synthesis of colchicine

Abstract

333ChemInform Abstract The thermal cycloaddition of the α-pyrone (I) with the ketal (II) yields the bicyclolactone (III) which is transformed to the amino compounds (IV) and (V). While (IV) directly yields the desired deacetamidocolchiceine (VI), its isomer (V) gives the tropolone (VII). The latter can be converted to (VI) according to a known procedure. (VI), in turn, has already been transformed to colchicine (VIII), a potent mitotic inhibitor. Cycloaddition of (I) with (II) under modest pressure yields the exo-cycloadduct (IX). All attempts to synthesize the compound (X) from this product are unsuccessful.

Inverse Electron Demand Diels–Alder Reactions of Heterocyclic Azadienes, 1-Aza-1,3-Butadienes, Cyclopropenone Ketals, and Related Systems. A Retrospective

“…The cycloaddition reactions of cyclopropenone ketals first found application in the total synthesis of colchicine . The first of the tropolone alkaloids to be identified, colchicine is a historically important antimitotic agent that inhibits cell division through tubulin binding and exhibits antitumor activity.…”

Enzymes in carbohydrate synthesis. Lipase-catalyzed selective acylation and deacylation of furanose and pyranose derivatives

“…acyl) blocking groups usually requires a series of steps involving protections and deprotections of the other hydroxyl groups present in the molecule. 2 Regioselective deprotection of polyacylated sugars is seldom observed.3,4…”

Gram-Scale, Seven-Step Total Synthesis of (−)-Colchicine

“…Taken together, despite being deceptively straightforward in the structures, colchicine ( 1 ) and allocolchicinoids are synthetic challenging targets; especially for colchicine ( 1 ) much attention has been oriented to its total synthesis in recent decades. Although several elegant routes have emerged, there was no genuinely practical synthesis of 1 for the past 60 years…”