Synthesis of the spiroketal core of integramycin

• Evgeny. V. Prusov

Beilstein J. Org. Chem. 2013, 9, 2446–2450, doi:10.3762/bjoc.9.282

• TES-protected alkene was somewhat lower, probably due to a partial cleavage of the protecting group during the acylation or hydrozirconation step. Finally, several conditions were studied for the spiroacetalization step. Exposure of the all-TBS protected ketone 17 to moderately strong acids, e.g. the

Stereoselective synthesis of the C79–C97 fragment of symbiodinolide

• Hiroyoshi Takamura,
• Takayuki Fujiwara,
• Isao Kadota and
• Daisuke Uemura

Beilstein J. Org. Chem. 2013, 9, 1931–1935, doi:10.3762/bjoc.9.228

• , Hiratsuka 259-1293, Japan 10.3762/bjoc.9.228 Abstract Symbiodinolide is a polyol marine natural product with a molecular weight of 2860. Herein, a streamlined synthesis of the C79–C97 fragment of symbiodinolide is described. In the synthetic route, a spiroacetalization, a Julia–Kocienski olefination, and a

• Sharpless asymmetric dihydroxylation were utilized as the key transformations. Keywords: Julia–Kocienski olefination; polyol marine natural product; Sharpless asymmetric dihydroxylation; spiroacetalization; symbiodinolide; Findings A 62-membered polyol marine natural product, symbiodinolide (1, Figure 1

• subsequent Sharpless AD [15], wherein the target molecule 8 could be prepared in two steps from the coupling. The carbon framework of 9 could be constructed through the stereoselective spiroacetalization of dihydroxyketone 11. First, we commenced the stereocontrolled synthesis of aldehyde 20 (Scheme 3