122271-91-4Relevant articles and documents
Total synthesis of hemibrevetoxin B
Morimoto, Masamichi,Matsukura, Hiroko,Nakata, Tadashi
, p. 6365 - 6368 (1996)
Total synthesis of hemibrevetoxin B was stereoselectively accomplished based on a novel double rearrangement-ring expansion of a 6,6-membered ether to a 7,7-membered ether, an exclusive 6-endo-cyclization of hydoxy styrylepoxide, and a direct introduction of a C-4 unit as the side chain on the A-ring.
Stereocontrolled Total Synthesis of Hemibrevetoxin B
Kadota, Isao,Yamamoto, Yoshinori
, p. 6597 - 6606 (2007/10/03)
The stereocontrolled total synthesis of hemibrevetoxin B (1) has been achieved in 56 steps and 0.75% overall yield from D-mannose. The intramolecular reaction of γ-alkoxyallylstannane with aldehyde is a key step for the present total synthesis. Thus, the BF3·OEt2-mediated reaction of 24 gave 6 as a sole product. We encountered difficulty in the synthesis of γ-alkoxyallylstannane 30 from the corresponding allyl ether 29 in which the γ-alkoxy substituent became sterically quite bulky. This problem was solved by developing the acetal cleavage method for the synthesis of γ-alkoxyallylstannanes. The cyclization of 38 proceeded smoothly to give the key intermediate 5 in a highly stereoselective manner. Construction of the α-vinyl aldehyde and (Z)-diene moieties were performed using Nicolaou's protocol.
Total synthesis of hemibrevetoxin B
Kadota, Isao,Jung-Youl, Park,Koumura, Nagatoshi,Pollaud, Guy,Matsukawa, Yasuhisa,Yamamoto, Yoshinori
, p. 5777 - 5780 (2007/10/02)
The total synthesis of Hemibrevetoxin B is described. A new cyclization approach, based on the Lewis acid mediated intramolecular cyclization of the γ-oxo-substituted allylic tin having an aldehyde group, produced the 6-6-7-7 polycyclic ether skeleton of
Total synthesis of hemibrevetoxin B and (7aα)-epi-hemibrevetoxin B
Nicolaou,Reddy, K. Raja,Skokotas, Golfo,Sato, Fuminori,Xiao, Xiao-Yi,Hwang
, p. 3558 - 3575 (2007/10/02)
The total synthesis of hemibrevetoxin B(1) and (7aα)-epi-hemibrevetoxin B (2) is described. The synthesis of the epimer (2) was achieved through a convergent approach involving coupling of the carboxylic acid 17 carrying the bicyclic pyran system with the hydroxy compound 31 containing the monocyclic pyran system, thionation of the resulting diester 32 to the dithionoester 33, photolytic closure to the oxepane enol ether 34, and hydroxy ketone cyclization to the dioxepane system 40. The Z-diene system was established using a selenyl-Wittig reaction followed by syn elimination of the selenoxide to the diene. The α-vinyl functionality was installed using the Eschenmoser's salt methodology. The synthesis of hemibrevetoxin B(1) was achieved through a linear approach involving sequential formation of the oxepane rings (65 → 67 → 73) using the method of thionolactone formation followed by nucleophilic addition and regio/stereoselective hydroboration (67 → 68, 75 → 76). Elaboration of the side chains was carried out in a similar fashion as described for the epimer. The stereochemistry of the ring junctures in 1 and 2 and intermediates leading to them was established by X-ray crystallographic analysis carried out on compounds 45 and 54. Biological studies with (7aα)-epi-hemibrevetoxin B (2) revealed no binding for this molecule to the brevetoxin receptors.
