Première hémisynthèse d'un composé de type taxane porteur d'un groupement oxétane en 4(20),5.

The Total Synthesis of Paclitaxel by Assembly of the Ring System

“…While establishing our strategy, we had a central goal secondary to the total synthesis: the route must be sufficiently flexible and practical to allow the preparation of many analogs unavailable from Nature or man's manipulation of the natural product. Relying on the previous work of other groups as well as our own studies, we envisaged the late formation of the oxetane (D) ring (36)(37)(38), attachment of the side chain (28)(29)(30)(31)(32), and oxygenation/reduction of the C13 position (39). Thus, we perceived the problem as limited to the assembly of Taxol's ABC ring system in either its fully functionalized form or a form that would serve as its progenitor.…”

Oxetanes as versatile building blocks in the total synthesis of natural products: An overview

“…Nicolaou and his co-workers were reported total synthesis of taxol and in 1994 [104][105][106][107]. They were described the construction of oxetane ring which was more challenging in the total synthesis of taxol in two pathways based on a taxoid skelton achieved by Potier's group [108] and on a C ring model system performed by Danishefsky's group [109].…”

Synthesis and Biological Evaluation of New 4‐Deacety‐1,7,9‐trideoxy‐10‐oxopaclitaxel via Sinenxan A

“…Because of intramolecular acetyl transfer, the C2 and C20 acetyl groups were removed at the same time to afford 14. The oxetane ring was formed according to Potier's procedure, [5] and subsequent benzoylation of the C2 hydroxyl group gave 15. [6a] Although acetylation of the C4 hydroxyl group of 15 under two conditions (1.5 equiv of DMAP, 20 equiv of Ac 2 O, Py, 508C and 1.5 equiv of LiHMDS, 08C, 30 min, then 1.3 equiv of AcCl) [6] were examined, 16 was not achieved, which can be explained by the fact that the C13 acetyl group and the C2 benzoyl group hinder the C4 hydroxyl group, making it less reactive.…”

“…13a,2a,20-Triacetoxy-4a,5a-dihydroxy-11-taxen-10-one (12) J ¼ 3.6 Hz, 11.6 Hz, 1H),5.53 (d, J ¼ 5.2 Hz, 1H), 4.52 (d, J ¼ 12 Hz, 1H), 4.08 (d, J ¼ 12 Hz, 1H), 3.90 (s, 1H), 3.16 (d, J ¼ 5.2 Hz, 1H), 2.88 (d, J ¼ 16 Hz, 1H), 2.70-2.62 (m, 2H), 2.34 (dd, J ¼ 4 Hz, 15.6 Hz, 1H), 2.23-2.08 (3s þ m, 11H), 1.91 (s, 3H), 1.80 -1.69 (m, 2H), 1.44 (s, 3H), 1.16-1.12 (m, 1H), 1.06 (s, 3H), 0.89 (s, 3H); 13 C NMR (100 MHz) d 203.1, 171.3, 170.1, 169.7, 144.3, 136.0, 73.5, 69.6, 68.6, 65.4, 58.7, 46.3, 41.9, 39.2, 35.7, 33.1, 31.0, 29.2, 27.8, 26.0, 24.4, 23.8, 21.6, 21.0, 20.8, 14.6. HRESIMS calcd.…”