WILEY‐VCH Acta Medica Okayama 0947-6539 22 6 2016 Stereodivergent Synthesis and Stereochemical Reassignment of the C79-C104 Fragment of Symbiodinolide 1984 1996 EN Hiroyoshi Takamura Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University Takayuki Fujiwara Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University Yohei Kawakubo Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University Isao Kadota Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University Daisuke Uemura Department of Chemistry, Faculty of Science, Kanagawa University We have synthesized eight possible diastereoisomers 3 a-h of the C79-C97 fragment of symbiodinolide (1) in a stereodivergent manner by utilizing a dithiane addition to the aldehyde as a key step. Comparison of the 13 C NMR chemical shifts of the natural product 1 and the synthetic products 3 a-h indicated that the relative stereostructure of this fragment in symbiodinolide (1) is that represented in 3 a or f. We have stereodivergently synthesized eight possible diastereoisomers of the C94-C104 fragment 4 a-h, and we have compared their 13 C NMR chemical shifts with those of the natural product, which established the relative stereochemistry of this fragment to be that described in diastereoisomers 4 a or e. By combining the stereostructural outcomes of the C79-C97 and C94-C104 fragments, we have proposed four candidate compounds of the C79-C104 fragment 2 a-d. We also synthesized diastereoisomers 2 a and b (2 a in the preceding article; Chem. Eur. J. 2015, DOI: 10.1002/chem.201503880) by a Julia-Kocienski olefination and diastereoisomers 2 c and d by a Wittig reaction. By comparing the 13 C NMR chemical shifts of natural symbiodinolide (1) with those of the synthetic products 2 a-d, we have reassigned the stereostructure of the C79-C104 fragment of natural product 1 to be that depicted in diastereoisomer 2 b. No potential conflict of interest relevant to this article was reported.