201142-29-2Relevant academic research and scientific papers
Ti(IV) promoted 1,3-dipolar cycloaddition of nitrones to vinyl ethers
Bayon, Pau,De March, Pedro,Figueredo, Marta,Font, Josep
, p. 15691 - 15700 (2007/10/03)
The 1,3-dipolar cycloaddition of nitrones to vinyl ethers is accelerated by Ti(IV) species. The efficiency of the catalyst parallels its complexation capacity. The use of Ti((i)prO)2Cl2 favours the formation of trans cycloadducts, presumably through an endo bidentate complex, in which the metal atom is simultaneously coordinated to the vinyl ether and to the cyclic nitrone or the Z isomer of the acyclic nitrones.
Total synthesis of sarcodictyins A and B
Nicolaou,Xu,Kim,Pfefferkorn,Ohshima,Vourloumis,Hosokawa
, p. 8661 - 8673 (2007/10/03)
The total synthesis of cytotoxic marine natural products possessing tubulin polymerization and microtubule stabilization properties, sarcodictyins A (7) and B (8), is described. Two related approaches to these target molecules have been developed, both utilizing (+)-carvone (9) as starting material. The first approach involves a stereoselective construction of acetylenic aldehyde 27 (Scheme 2) while the second approach proceeds through a more direct but less selective sequence to the similar intermediate 36 (Scheme 3). Both strategies involve ring closures of the acetylenic aldehyde precursors to 10-membered rings under basic conditions followed by elaboration and selective reduction of the acetylenic linkage to a cis double bond. This promotes bridging to form the required tricyclic skeleton of the sarcodictyins (27 → 37 → 38 → 39 4, Scheme 4 and 37 → 44 → 45 → 46 → 47 → 42, Scheme 5) and (36 → 48 → 45, Scheme 6). Installation of the (E)- N(6')-methylurocanic acid residue was achieved by esterification with mixed anhydride 52, while the C-3 ester moieties were installed by standard deprotection, oxidation, and esterification procedures.
