Selective chromic acid oxidation of alcohols in the erythromycin series in consequence of conformational immobility

✍ Scribed by E.J. Corey; Lawrence S. Melvin Jr.

• Publisher: Elsevier Science
• Year: 1975
• Tongue: French
• Weight: 224 KB
• Volume: 16
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)72022-3

✦ Synopsis

Strong evidence has accumulated in favor of a conformation for the erythronolide rin& the nucleus of the erythromycin antibiotics, which is approximated by the stereoformula L. '-' This and 2, R,+R,= 0 i.1 R,=OH, R3 =H 5, R,=H, R,=OH closely related3 three-dimensional arrangements lie in a deep well in the conformational potential energy surface, since the pmr spectrum continues to exhibit sharp peak9 and discrete fine structure due to spin-spin coupling even at 110" C.2 The 3, I-isopropylidene derivative of erythronolide B w4 also possesses this geometry for the macrolide ring as is clear from the correspondence of coupling constants observed for zand various derivatives2 of L. The conformational stability of the erythronolide macro ring and the occurrem+e at C-11 of an axial hydroxyl and a difficultly accessible equatorialfneide hydrogen suggested that the 11-hydroxyl function might be sufficiently resistant to chromic acid