C-N Ring Construction: The Glorius Synthesis of ent-Monomorine
Ryan Gilmour of the Westfälische Wilhelms-Universität Münster employed (Chem. Eur. J. 2014, 20, 794. DOI: 10.1002/chem.201303586) an organocatalyst to direct the enantioselective aziridination of 1 to 2. Vanessa Kar-Yan Lo and Chi-Ming Che of Hong Kong University devised (Angew. Chem. Int. Ed. 2014, 53, 2982. DOI: 10.1002/anie.201309888) a Ru catalyst for the enantioselective aziridination (not illustrated) of terminal alkenes. Shu-Li You of the Shanghai Institute of Organic Chemistry and Aiwen Lei of Wuhan University described (Angew. Chem. Int. Ed. 2014, 53, 2443. DOI: 10.1002/anie.201309081) the Pd-mediated carbonylation of 3 to the β-lactam 4.
Professor You reported (J. Am. Chem. Soc. 2014, 136, 6590. DOI: 10.1021/ja5028138) the enantioselective allylation of a pyrrole 5 to the imine 7. Maria-Paz Cabal and Carlos Valdés of the University of Oviedo showed (Eur. J. Org. Chem. 2014, 1672. DOI: 10.1002/ejoc.201301587) that the cyclization of 8 to 9 proceeded with predictable high diastereocontrol. In one pot, Darren J. Dixon of the University of Oxford combined (ACS Catal. 2014, 4, 634. DOI: 10.1021/cs401008v) 10 and 11 to give 12 in high ee. The addition of 13 to 14 described (Nature Chem. 2014, 6, 47. DOI: 10.1038/nchem.1796) by Takashi Ooi of Nagoya University set two adjacent quaternary centers with control of both relative and absolute configuration.
Scott E. Denmark of the University of Illinois devised (J. Am. Chem. Soc. 2014, 136, 8915. DOI: 10.1021/ja5046296) a catalyst for the enantioselective electrophilic cyclization of 16 to 17 with control of sidechain stereochemistry. Using commercial acetone cyanohydrin 19, Christian V. Stevens of Ghent University cyclized (Eur. J. Org. Chem. 2014, 1296. DOI: 10.1002/ejoc.201301397) 18 to the nitrile 20. George W. J. Fleet, also of the University of Oxford, used (Eur. J. Org. Chem. 2014, 2053. DOI: 10.1002/ejoc.201301705) similar conditions to convert the sugar-derived acetonide 21 into 22. Michael B. Tropak of the University of Toronto and Dilip P. Dhavale of the University of Pune showed (J. Org. Chem. 2014, 79, 4398. DOI: 10.1021/jo500328u) that the nitrone derived from 21 added to an alkene 23 with high facial selectivity, leading to the piperidine 24.
In the course of a synthesis of Syringolin A, Satoshi Ichikawa of Hokkaido University effected (Angew. Chem. Int. Ed. 2014, 53, 4836. DOI: 10.1002/anie.201402428) intramolecular Ugi three-component coupling of the isonitrile 25, the acid 26 and the amine 27, leading to the macrolactam 28. Jennifer L. Stockdill of Wayne State University stitched together (Org. Lett. 2014, 16, 1072. DOI: 10.1021/ol4034868) two of the rings of 30 by the radical cascade cyclization of the alkyne 29.
The alkaloid Monomorine, presumably derived from ants, is found in the skins of frogs. Frank Glorius, also of Westfälische Wilhelms-Universität Münster, developed (Angew. Chem. Int. Ed. 2013, 52, 9500. DOI: 10.1002/anie.201302218) a synthesis of ent-Monomorine 33 based on the enantioselective hydrogenation of the prochiral 31.