Organic Chemistry Portal
Organic Chemistry Highlights

Monday, November 13, 2017
Douglass F. Taber
University of Delaware

C-N Ring Construction: The Makabe Synthesis of Isosolenopsin

Stephen L. Buchwald of MIT devised (J. Am. Chem. Soc. 2017, 139, 8428. DOI: 10.1021/jacs.7b04816) the enantioselective cyclization of 1 to the aziridine 2. Tsutomu Kimura of the Tokyo University of Science designed (Tetrahedron 2017, 73, 2623. DOI: 10.1016/j.tet.2017.03.045) the net N-H insertion that converted 3 to 4.

Carlo Sa of the Universidade de Santiago de Compostela effected (ACS Catal. 2017, 7, 992. DOI: 10.1021/acscatal.6b02929) the cross metathesis of the alkyne 5 with TMS diazomethane 6 to give the epoxide 7. Ying-Chun Chen of Sichuan University assembled (Org. Lett. 2017, 19, 1874. DOI: 10.1021/acs.orglett.7b00636) 10 by combining 8 with 9. Adrien Quintard of Aix-Marseille University added (Org. Lett. 2017, 19, 722. DOI: 10.1021/acs.orglett.7b00014) 12 to 11 to give 13. Yonggui Robin Chi of Nanyang Technoogical University used (Angew. Chem. Int. Ed. 2017, 56, 4201. DOI: 10.1002/anie.201700045) a carbene catalyst to mediate the assembly of 16 by the combination of 14 with 15.

Xiao-Chen Wang of Nankai University showed (Angew. Chem. Int. Ed. 2017, 56, 5817. DOI: 10.1002/anie.201702304) that the pyridine 17 could be reduced to the piperidine 18, preserving the distal alkene. Robert S. Paton and Darren J. Dixon of the University of Oxford achieved (Angew. Chem. Int. Ed. 2017, 56, 5834. DOI: 10.1002/anie.201612048) high ee in the cyclization of 19 to 20. Xiaofeng Tong of Changzhou University used (Org. Biomol. Chem. 2017, 15, 4803, DOI: 10.1039/C7OB00762K; Chem. Commun. 2017, 53, 4270, DOI: 10.1039/C7CC01488K) a Pd catalyst to set the absolute configuration of the cyclic quaternary center of 22 by the cyclization of 21. Dipankar Koley of the Central Drug Research Institute effected (Org. Lett. 2017, 19, 274. DOI: 10.1021/acs.orglett.6b03605) an enantioselective version of the classic Speckamp cyclization, converting 23 to 24.

Sundarababu Baskaran of the Indian Institute of Technology Madras combined (Chem. Eur. J. 2017, 23, 533. DOI: 10.1002/chem.201604376) the amino alcohol 26 with the ribose tosylate 25 to give the bicyclic methyl ketone 27. Timo Nuijens of EnzyPep B.V. reported (Adv. Synth. Catal. 2017, 359, 2050. DOI: 10.1002/adsc.201700314) on the modified peptiligase omniligase-1, that efficiently converted a variety of peptides and peptoids 28 to the cyclic peptide 29.

Isosolenopsin (32), isolated from the venom of the fire ant Solenopsis invicta, is a potent and selective inhibitor of neuronal nitric oxide synthase. En route to 32, Hidefumi Makabe of Shinshu University optimized (Heterocycles 2017, 94, 286. DOI: 10.3987/COM-16-13631) the diastereoselective cyclization of 30 to 31.

X-ray crystallography has been extended to non-crystalline compounds! Makoto Fujita of the University of Tokyo designed (Chem. Asian. J. 2017, 12, 1057. DOI: 10.1002/asia.201700515) a crystalline sponge. After the oily guest compound (5-10 µg) is absorbed in the sponge, x-ray analysis shows the structure.

D. F. Taber, Org. Chem. Highlights 2017, November 13.