Organic Chemistry Portal
Organic Chemistry Highlights

Monday, December 12, 2011
Douglass F. Taber
University of Delaware

Organocatalyzed C-C Ring Construction: The Thomson Synthesis of Streptorubin B

Jinxing Ye of the East China University of Science and Technology used (Tetrahedron Lett. 2011, 52, 2715. DOI: 10.1016/j.tetlet.2011.03.079) the Hayashi catalyst to direct the addition of 2 to 1, to give the cyclopropane 3. Jia-Rong Chen and Wen-Jing Xiao of Central China Normal University employed (J. Org. Chem. 2011, 76, 281. DOI: 10.1021/jo101699r) a urea catalyst for the addition of 5 to 4.

Yasumasa Hamada of Chiba University devised (Tetrahedron Lett. 2011, 52, 987. DOI: 10.1016/j.tetlet.2010.12.067) a different urea catalyst for the addition of 7 to 8, to control both the absolute and relative configuration of 9. Jiyong Hong of Duke University showed (Tetrahedron Lett. 2011, 52, 2468. DOI: 10.1016/j.tetlet.2011.03.008) that the imidazolium-mediated cyclization of 10 proceeded with high diastereoselectivity, to give 11.

Yixin Lu of the National University of Singapore optimized (J. Am. Chem. Soc. 2011, 133, 1726. DOI: 10.1021/ja1106282) a dipeptide-derived phosphine to catalyze the addition of 12 to 13. Karl A. Scheidt of Northwestern University combined (Angew. Chem. Int. Ed. 2011, 50, 1678. DOI: 10.1002/anie.201005908) a triazolium catalyst with super-stoichiometric Ti(O-iPr)4 to effect the addition of 15 to 4, to give 16.

En route to Malyngamide C, Xiao-Ping Cao of Lanzhou University condensed (J. Org. Chem. 2011, 76, 3946. DOI: 10.1021/jo2003852) the prochiral commercial monoketal 17 with nitrosobenzene, using proline as organocatalyst, to prepare 18. Hong Wang of Miami University showed (Angew. Chem. Int. Ed. 2011, 50, 3484. DOI: 10.1002/anie.201100160) that a lanthanide-complexed α-amino amide was effective for catalyzing the addition of the prochiral 19 to 4, to give 20.

Alexandre Alexakis of the Universite de Geneve and John C. Stephens of the National University of Ireland, Maynooth established (Angew. Chem. Int. Ed. 2011, 50, 5095. DOI: 10.1002/anie.201100804) that the Hayashi catalyst was effective for mediating the addition of 22 to 21, to give the diene 23. Ying-Chun Chen of Sichuan University and Karl Anker Jørgensen of Aarhus University used (J. Am. Chem. Soc. 2011, 133, 5053. DOI: 10.1021/ja1112194) the same catalyst for the addition of 24 to 25. The Hayashi catalyst appeared again in the report (Chem. Comm. 2011, 47, 3828. DOI: 10.1039/C1CC10245A) by Magnus Rueping of RWTH Aachen University of the addition of 27 to 28. Xiaohua Liu and Xiaoming Feng, also of Sichuan University, used (Org. Lett. 2011, 13, 936. DOI: 10.1021/ol1029832) a Cinchona-derived catalyst to add 29 to 30.

Regan J. Thomson, also of Northwestern University, took advantage (J. Am. Chem. Soc. 2011, 133, 1799. DOI: 10.1021/ja109165f) of the proline-mediated intramolecular aldol condensation of 32 to prepare 34. Subsequent oxy-Cope rearrangement established the ten-membered ring of Streptorubin B (35).

D. F. Taber, Org. Chem. Highlights 2011, December 12.