title: An isolable acyclic hemiacetal of ansamitocin P-3.
abstract: During impurity analysis of maytansinol (2), produced from the reduction of ansamitocin P-3 (AP-3, 1), a surprisingly stable acyclic hemiacetal (4) was isolated. A combination of 1D and 2D NMR experiments, along with liquid chromatography-mass spectrometry data was used to confirm the structure. Comparison of NMR data to the previously reported bridged acetal (3), a by-product of AP-3 reduction, supports reassignment of the latter to the former. Additionally, ROESY data, in conjunction with minimum energy calculations, support intramolecular hydrogen bonding that is involved in stabilizing the hemiacetal. This report adds another example to the very short list of isolable acyclic hemiacetals.
authors.affiliation: Department of Small Molecule Pharmaceutical Sciences, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA. Segraves.Nathaniel@gene.com
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Segraves
authors.forename: Derrick
authors.initials: D
authors.lastname: Yazzie
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Deese
mesh_terms: D002853:Chromatography, Liquid; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D013058:Mass Spectrometry; D008453:Maytansine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D015394:Molecular Structure; D011522:Protons; D012015:Reference Standards
chemical_list: D011522:Protons; D008453:Maytansine; C015682:ansamitocins; D003903:Deuterium