Tetracycloxides. I. A New Class of Tetracycline Derivatives

Chemical Modification of the Tetracyclines

“…8) (BLACKWOOD and STE-PHENS 1965;ESSE et al 1964 a;HLAvKA and BOOTHE 1973). U nder anhydrous conditions the C6 hydroxy group of compound (51) or (52) reacts with the 4-imino group to produce compounds (53) and (54) (ESSE et al 1964a;BLACKWOOD and STEPHENS 1964;. These compounds are extremely unstable and are readily hydrolyzed into 4-keto compounds (55) and (56) which in turn undergo hemiketal formation with the C6 hydroxyl to give (57) and (58).…”

Facile conversion of tetracycline antibiotics to 4,11a-bridged derivatives via oxidative mannich cyclization

“…The tertiary 4-iminium intermediate (3 in Scheme 1, 10 in Scheme 2 and 18 in Scheme 3) was previously proposed by Esse et al 11 during their investigation on the reaction of 6-demethyltetracycline with mercuric acetate, which, as the authors believed, led to the formation of 4,6-bridged 22 (Scheme 3). Our reexamination found that the reaction initially afforded a mixture of at least of two products as observed by 13 C NMR after 1 h with 1.2 equivalents of Hg(OAc) 2 .…”

Oxidation of .beta.-lactone dimer of dimethylketene

“…The oxidation of 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid j3-lactone (1) with hydrogen peroxide in slightly basic aqueous media yields as final products isopropyl isobutyrate and carbon dioxide. There was evidence of the intermediate formation of sodium isopropyl dimethylmalonate (2).…”