Electrooxidative tricyclic 6-7-6 fused-system domino assembly to allocolchicines by a removable radical strategy

Natural allocolchicine and analogues derived thereof a tricyclic 6-7-6-system have been found as key scaffold of various biologically relevant molecules. However, the direct preparation of the allocolchicine motif remains difficult to date. Herein, we report on an electrooxidative radical cyclization of biarylynones with various carbon- and heteroatom-centered radical precursors via a sequential radical addition/7-endo-trig/radical cyclization domino reaction. This approach provides a step-economical and strategically novel disconnection for the facile assembly of a wide range of carbocyclic 6-7-6 fused ring systems. Remarkably, the sulfonyl group on the products could be easily removed by photocatalysis at room temperature with high yields.

Allocolchicines─Synthesis with Electro-organic Key Transformations

The naturally occurring colchicine and allocolchicines in the meadow saffron are potentially active ingredients for cancer therapy. A concise protocol for the sustainable synthesis of allocolchicines using up to two electro-organic key transformations is demonstrated. This straightforward synthesis of N-acetylcolchinol methyl ether in a five-step protocol was adopted using protecting groups to enable access to N-acetylcolchinol and the phosphate derivative ZD6126.

Pyrinap ligands for enantioselective syntheses of amines

Amines are a class of compounds of essential importance in organic synthesis, pharmaceuticals and agrochemicals. Due to the importance of chirality in many practical applications of amines, enantioselective syntheses of amines are of high current interest. Here, we wish to report the development of (R,R_a)-N-Nap-Pyrinap and (R,S_a)-N-Nap-Pyrinap ligands working with CuBr to catalyze the enantioselective A³-coupling of terminal alkynes, aldehydes, and amines affording optically active propargylic amines, which are platform molecules for the effective derivatization to different chiral amines. With a catalyst loading as low as 0.1 mol% even in gram scale reactions, this protocol is applied to the late stage modification of some drug molecules with highly sensitive functionalities and the asymmetric synthesis of the tubulin polymerization inhibitor (S)-(-)-N-acetylcolchinol in four steps. Mechanistic studies reveal that, unlike reported catalysts, a monomeric copper(I) complex bearing a single chiral ligand is involved in the enantioselectivity-determining step.

Colchicine Alkaloids and Synthetic Analogues: Current Progress and Perspectives

Colchicine, the main alkaloid of Colchicum autumnale, is one of the most famous natural molecules. Although colchicine belongs to the oldest drugs (in use since 1500 BC), its pharmacological potential as a lead structure is not yet fully exploited. This review is devoted to the synthesis and structure-activity relationships (SAR) of colchicine alkaloids and their analogues with modified A, B, and C rings, as well as hybrid compounds derived from colchicinoids including prodrugs, conjugates, and delivery systems. The systematization of a vast amount of information presented to date will create a paradigm for future studies of colchicinoids for neoplastic and various other diseases.

N-Acetylcolchinol Methyl Ether (a Natural Product); Suhailamine (a Phantom Natural Product)

The reported characterization data for the allocolchicinoid alkaloid suhailamine, isolated from Colchicum decaisnei and known to have an erroneous structure, have been reanalyzed. This analysis has led to the current proposal that suhailamine has the same structure as N-acetylcolchinol methyl ether (NCME), an assertion that is supported by comparison with previously reported data for NCME. Suhailamine is therefore a phantom natural product, while NCME represents a naturally occurring allocolchicinoid rather than a purely synthetic entity.

Total Synthesis of (±)-Allocolchicine and Its Analogues Using Co-Catalyzed Alkyne [2 + 2 + 2]-Cyclotrimerization

The total synthesis of (±)-allocolchicine has been completed by employing cobalt-catalyzed alkyne [2 + 2 + 2]-cyclotrimerization as the key reaction. The essential diyne has been synthesized from easily available 3,4,5-trimethoxybenzaldehyde following simple chemical transformations. In general, the cycloaddition gave a mixture of C(9) and C(10) isomers thus allowing the synthesis of both allocolchicine and its C(10)-carboxylate. Because this cycloaddition was employed at the penultimate stage, it allowed the synthesis of various analogues having the diverse functionality at C(9) and/or C(10) of ring C.

Colchicine metallocenyl bioconjugates showing high antiproliferative activities against cancer cell lines

Ferrocenyl and ruthenocenyl conjugates with colchicine have been synthesised and their cytotoxic activity, influence on the cell cycle, and interactions with tubulin were evaluated.

Synthesis and cytostatic properties of polyfunctionalized furanoallocolchicinoids

A series of furan-based allocolchicinoids was prepared from commercially available colchicine via a nine-step reaction sequence. Cytostatic activity, cell cycle arrest, apoptosis, tubulin and F-actin expression were studied in vitro in 2D and 3D cultures of normal and tumor epithelial keratinocytes, endothelial and mesenchymal cells. Among the prepared furanoallocolchicine analogues, 14a and 7a displayed the most pronounced anti-cancer activity. These compounds induced two types of effects: (a) cell cycle arrest in the G2/M phase as a direct consequence of effective tubulin binding (metaphase effect), and (b) pronounced cell stress (as evidenced by the overexpression of tubulin and F-actin), which was caused by the hyperpolarization of mitochondrial and lysosomal membranes (interphase effect).

Copper-catalyzed cascade annulation between α-bromocarbonyls and biaryl or (Z)-arylvinylacetylenes enabling a direct synthesis of dibenzocycloheptanes and related compounds

Copper-catalyzed cascade annulation of γ,δ-unsaturated α-bromocarbonyls with biaryl or (Z)-arylvinylacetylenes is presented, giving an expeditious access to dibenzocycloheptanes and related compounds in moderate to high yields.

Stereoselective synthesis of highly functionalized indanes and dibenzocycloheptadienes through complex radical cascade reactions

Two highly stereoselective radical-mediated syntheses of densely functionalized indanes and dibenzocycloheptadienes from ortho-vinyl- and ortho-vinylaryl-substituted N-(arylsulfonyl)-acrylamides, respectively, are presented here. The chemoselective addition of in situ generated radicals (X(·)) onto the styrene moieties triggers an unprecedented reaction cascade, resulting in the formation of one new C-X bond and two new C-C bonds, a formal 1,4-aryl migration, and the extrusion of SO2 to generate an amidyl radical intermediate. This intermediate, upon H abstraction, leads to the observed 5- and 7-membered ring carbocyclic products, respectively, in a highly efficient manner.

Synthesis of indole-derived allocolchicine congeners exhibiting pronounced anti-proliferative and apoptosis-inducing properties

The synthesis and biological assessment of indole-based allocolchicine congeners with potent anti-proliferative and apoptosis-inducing activity are reported.