Ulapualides tris-oxazoles

Chattopadhyay, S. K., and Pattenden, G. (1998). Total synthesis of ulapualide A, a novel tris-oxazole containing macrolide from the marine nudibranch Hexabranchus sanguineus. Tetrahedron Lett. 39,6095-6098. 

Panek and co-workersdescribed syntheses of suitably bis-functionalized tris-oxazoles as intermediates leading to kabiramide C, halichondramide, and ulapualide A based on sequential application of a modified Hantzsch condensation methodology (Scheme 1.395). For example, condensation of cinnamide with ethyl... 

Panek s group ° employed the Schlosser-Wittig olefination reaction of an in situ-generated tris-oxazole phosphonium salt to incorporate the trans double bond of an advanced intermediate leading to ulapualide A (Scheme 1.397). Model studies that precedent this work were described in Scheme 1.298. Thus reaction of 1560 with 1561 in the presence of excess triethylphosphine and one equivalent of LDA generated 1562 in excellent yield as a single double-bond isomer. This result was noteworthy in that it demonstrated the viability of this type of bond construction in the presence of a potentially labile p-alkoxy substituent. 

Subsequently, Kempson and Pattenden " applied this strategy to prepare a model for the complete tris-oxazole macrolide core of ulapualides (Scheme 1.402). 

Pattenden, G., Ashweek, N.J., Baker-Glenn, C.A.G., Kempson, J., Walker, G.M., and Yee, J.G.K (2008) Total synthesis of (-)-ulapualide A, a novel tris-oxazole macrolide from marine nudibranchs, based on some biosynthesis speculation. Org. Biomol. Chem., 6,1478-1497. 

Knight, D.W., Pattenden, G., and Rippon, D.E. (1990) Synthesis of the tris-oxazole ring system of ulapualides. Synlett, 36-37. 

Chattopadhyay, S.K. and Pattenden, G. (1995) Synthetic studies towards novel tris-oxazole based macrolides of marine origin. Stereocontrolled synthesis of the C20-C35 fragment in ulapualide A. Tetrahedron Lett., 36, 5271-5274. 

Panek, J.S. and Beresis, R.T. (1996) Studies directed toward the synthesis of ulapualide A. Asymmetric synthesis of the C8-C25 tris-oxazole fragment/. Org. Chem., 61, 6496-6497. 

Chattopadhyay S.K. and Pattenden, G. (1997b) Towards a total synthesis of ulapualide A — a concise synthesis of the tris-oxazole macrolide core and entire carbon skeleton. Synlett, 1345-1348. 

Chattopadhyay, S.K. and Pattenden, G. (2000) A total synthesis of the unique tris-oxazole macrolide ulapualide A produced by the marine nudibranch Hexabranchus sanguineus. J. Chem. Soc. Perkin Trans. I. 2429-2454. 

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