Efficient synthesis of onoceranediol from 12-hydroperoxy-8α,12-epoxy-11-bishomodrimane

Abstract

An efficient one step synthesis of the diacetate of the tetracyclic triterpenoid onoceranediol (4) by radical cleavage of the readily available 12 hydroperoxy 8α,12 epoxy 11 bishomo drimane is described. Drim 9(11) en 8α yl acetate (7) is formed in this reaction as a by product. Onoceranediol diacetate 4 is converted into onoceranediol on treatment with LiAlH 4 , and acetate 7 is transformed into drim 9(11) en 8α ol on saponification.

Regioselective 1,2-Diol Rearrangement by Controlling the Loading of BF3·Et2O and Its Application to the Synthesis of Related Nor-Sesquiterene- and Sesquiterene-Type Marine Natural Products

“…As shown in Scheme , reduction of the lactone functionality of 11 using DIBAL-H afforded lactol 12 , which was converted to iodoformate 13 via Suárez’s carbon–carbon bond cleavage strategy. Following Baran’s procedure, dehydroiodination of iodoformate 13 with AgF in pyridine and subsequent reaction with K 2 CO 3 afforded enol 14 in 80% overall yield from sclareolide. Ozonolysis of enol 14 under the classical ozonization reaction conditions generated α-hydroxy ketone 15 in 95% yield, which underwent reduction with NaBH 4 to give 1,2-decalindiol 10a in 98% yield.…”

Bioinspired synthesis of pentacyclic onocerane triterpenoids

“…Although data from a single crystal suitable for X-ray crystallography was obtained, the absolute configuration could not be determined. 6 Previous synthetic work on the onceranes 7 – 10 was focused on the tetracyclic C 2 -symmetrical congeners onocerandiol ( 5 ) 11 – 14 and α-onocerin ( 6 ). 15 – 22 The biosynthesis of onoceranoxide ( 7 ) 23 and α-onocerin ( 6 ) via 8 24 , 25 was hypothesized to proceed via cyclization of squalene and diepoxysqualene, respectively ( Scheme 1 ).…”

Scalable, Divergent Synthesis of Meroterpenoids via “Borono-sclareolide”

“…Thus, DIBAL-mediated reduction of 4 resulted in sclaral ( 12 ; Scheme ), which upon exposure to the hypoiodite-mediated C–C bond cleavage conditions of Suárez (PIDA/I 2 / h ν) delivered iodoformate 6 (characterized by X-ray crystallographic analysis). A two-step dehydroiodination/hydrolysis procedure (AgF in pyridine followed by K 2 CO 3 in methanol) afforded the sponge metabolite (+)-drim-9(11)-en-8α-ol ( 9 ) in 84% overall yield from 4 , without the use of chromatographic separation and on decagram scale for each transformation. This route constitutes the highest yielding and most efficient synthesis of 9 to date.…”