Hydroxylation with ozone on silica gel. The synthesis of 1.alpha.,25-dihydroxyvitamin D3

Synthesis and Electrochemical Properties of Phthalocyanine–Fullerene Hybrids

“…One of these involves the addition of an azomethine ylide, prepared in situ from the corresponding formyl derivative 5, across a fullerene 6:6 ring juncture, and the other involves the statistical condensation of two different substituted phthalonitriles, one of them (8) bearing the C 60 moeity covalently attached. Formylphthalocyanines 5 a, b were synthesized by means of an oxidative cleavage reaction of 4 a, b, using polymer-supported osmium tetroxide and sodium periodate, [16] or ozone at À 78 8C in dichloromethane as solvent, [17] as oxidizing agents (Scheme 2). [13] For these purposes, metal-free tri-tert-butyl-iodophthalocyanine (3 a) and tri-tert-butyl-iodophthalocyaninatozinc(ii) complex (3 b) [4a, 14] were prepared from the condensation reaction of 4-tert-butylphthalonitrile with 4-iodophthalonitrile (2) under the appropriate conditions (Scheme 1).…”

The Ozonolysis of Terpenoids, a Pandora's Box of by-Products

“…38 The method has also been developed for the introduction of a C25 hydroxyl group in the synthesis of lα,25dihydroxyvitamin D 3 . 39,40 A GC/MS study has shown that the ozone released from silica:ozone contains O 6 and O 9 . 41 The formation and reactivity of these species could have wider implications for the chemistry of ozone on surfaces.…”

Regio‐ and Stereoselective Functionalizations of Tricyclo [3.3.0.02,8]octan‐3‐one, a Potential Synthon for Polycyclopentanoid Terpenes and Prostacyclin Analogs. Preliminary Communication

“…An attempt failed to directly oxidize ring A and form the 3,7-diketone by the action of ozone on 1 when adsorbed on silica gel [7]. See [8] for a cyclopropyl ketone cleavage by another Mazur-type [9] reagent, trimethylsilyl trifluoroacetate, which, however, was followed by a deep-seated skeletal rearrangement.…”

“…Moreover, facile hydrolysis of b with El=CH3 is unlikely. One may speculate that the electron-rich double bond of a (EZ=CH3, (CH3)3Si) could act as a (possibly internal) nucleophile for proton abstraction from C (7), leading directly from a to 7 (path iii).…”