10.1021/ja981062g.s001 K. C. Nicolaou K. C. Nicolaou J. Y. Xu J. Y. Xu S. Kim S. Kim J. Pfefferkorn J. Pfefferkorn T. Ohshima T. Ohshima D. Vourloumis D. Vourloumis S. Hosokawa S. Hosokawa Total Synthesis of Sarcodictyins A and B American Chemical Society 1998 sarcodictyin anhydride 52 Total Synthesis tricyclic skeleton acetylenic aldehyde 27 acetylenic linkage ring closures esterification procedures cytotoxic marine tubulin polymerization target molecules Scheme microtubule stabilization properties acetylenic aldehyde precursors stereoselective construction approach proceeds 1998-08-13 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Total_Synthesis_of_Sarcodictyins_A_and_B/3670185 The total synthesis of cytotoxic marine natural products possessing tubulin polymerization and microtubule stabilization properties, sarcodictyins A (<b>7</b>) and B (<b>8</b>), is described. Two related approaches to these target molecules have been developed, both utilizing (+)-carvone (<b>9</b>) as starting material. The first approach involves a stereoselective construction of acetylenic aldehyde <b>27</b> (Scheme ) while the second approach proceeds through a more direct but less selective sequence to the similar intermediate <b>36</b> (Scheme ). Both strategies involve ring closures of the acetylenic aldehyde precursors to 10-membered rings under basic conditions followed by elaboration and selective reduction of the acetylenic linkage to a <i>cis</i> double bond. This promotes bridging to form the required tricyclic skeleton of the sarcodictyins (<b>27</b> → <b>37</b> → <b>38</b> → <b>39</b> → <b>4</b>, Scheme and <b>37</b> → <b>44</b> → <b>45</b> → <b>46</b> → <b>47</b> → <b>42</b>, Scheme ) and (<b>36</b> → <b>48</b> → <b>45</b>, Scheme ). Installation of the (<i>E</i>)-<i>N</i>(6‘)-methylurocanic acid residue was achieved by esterification with mixed anhydride <b>52</b>, while the C-3 ester moieties were installed by standard deprotection, oxidation, and esterification procedures.