Synthesis of the Tetracyclic Bis(acetal) Lactone Portion of Saudin

Abstract

Two synthetic approaches towards the synthesis of the tetracyclic lactone 4, containing the caged bis(acetalic) backbone of Saudin, were explored. Both sequences included the utilization of the known epoxy-acetal 3, prepared stereoselectively by means of an intramolecular radical cyclization, as the common key intermediate, allowing total control over the

Enantioselective synthesis of a taxol C ring

“…In this reaction, some decomposition was always observed, probably due to partial oxidation of the BOM ether by ozone. These results are in stark contrast with the observations of Cravero et al 10 , who showed that oxidation of a compound similar to 10 could be performed with ruthenium dioxide and sodium periodate, but not with ozone. Reduction of keto acid 11 with LiAlH 4 gave diol 12 as a 1:1 mixture of diastereomers.…”

seco‐Labdanes: A Study of Terpenoid Structural Diversity Resulting from Biosynthetic C−C Bond Cleavage

“…In addition to the work of Winkler and Boeckman, partial syntheses of saudin ( 47 ) have been reported by both the Labadie and Stoltz groups [106–112] . Labadie and co‐workers established access to the bisketal core of saudin ( 47 ) from tetralone ( 167 ) by employing a radical cyclisation of bromide 168 or iodide 169 , and an acid‐catalysed transketalisation of 170 to give the core structure 171 (Scheme 4 A).…”

“…Labadie and co‐workers established access to the bisketal core of saudin ( 47 ) from tetralone ( 167 ) by employing a radical cyclisation of bromide 168 or iodide 169 , and an acid‐catalysed transketalisation of 170 to give the core structure 171 (Scheme 4 A). [109] …”

Ozonolysis of Unsaturated Carbonyl Compounds and Alcohols

“…Ozonolysis of 3β-acetoxy-5α-lanost-8-ene (68a) and 5α-lanost-8-en-3-ol (68ab) gave the corresponding epoxides 69a (47%) and 69b (56%) (Scheme 27). Ozone acts as epoxidating agent in the reaction with sterically hindered triterpenoids (70 → 71, Scheme 28) [28][29][30][31] and steroidal olefins [32,33]. These reactions cannot be interpreted in terms of the concerted Criegee mechanism.…”