Reactions of Alkenes: The Li Synthesis of Daphenylline
Xiang-Guang Meng of Sichuan University developed an iron catalyst for the oxidation of a terminal alkene 1 to the epoxide 2 (Tetrahedron Lett. 2018, 59, 2436. ). Alexandros L. Zografos of the Aristotle University of Thessaloniki oxidized the alkene 3 to the allylic chloride 4 (J. Org. Chem. 2017, 82, 8710. ). M. Christina White of the University of Illinois oxidized the alkene 5 to the allylic amine 6 (J. Am. Chem. Soc. 2018, 140, 3202. ). Song Lin of Cornell University devised the electrochemical oxidation of the alkene 7 to the bis azide 8 (Science 2017, 357, 575; ; Nature Protocols 2018, 13, 1725, ).
Zhaomin Hou of RIKEN found conditions for the selective coupling of the sulfide 9 with the alkene 1, leading to 10 (J. Am. Chem. Soc. 2018, 140, 114. ). The product sulfide could inter alia be converted into the alkene by Ramberg-Bäcklund rearrangement of the corresponding sulfone. Deberaj Mukherjee of the Indian Institute of Integrative Medicine coupled the alkene 1 with the glycal 11 to give 12 (Org. Biomol. Chem. 2018, 16, 2666. ).
Christoforos G. Kokotos of the National and Kapodistrian University of Athens used photochemical activation to prepare 15 by the addition of 14 to 13 (Org. Lett. 2018, 20, 36. ). Yu-Peng He of Liaoning Shihua University and Lingling Chu of Donghua University showed that photochemical activation was also effective for promoting the addition of 17 to 16 to give 18 (Chem. Commun. 2018, 54, 3162. ). Kami L. Hull, also of the University of Illinois, used a Cu catalyst to mediate the preparation of 20 by the addition of the bromoester 19 and aniline to the alkene 1 (J. Am. Chem. Soc. 2018, 140, 58. ). Shaolin Zhu of Nanjing University showed that under Ni catalysis, migration of the alkene of 21 preceded coupling with 22, leading to 23 (Angew. Chem. Int. Ed. 2018, 57, 4058. ). Xi-Sheng Wang of the University of Science and Technology of China reported related results (Tetrahedron Lett. 2018, 59, 2302. ).
Xiao-Feng Wu of the Universität Rostock devised conditions for the carbonylation of 1 in the presence of acetonitrile and the alcohol 24, leading to 25 (Chem. Commun. 2018, 54, 1984. ). M. Kevin Brown of Indiana University developed a protocol for the borylative arylation of 1 to give 26, ready for further coupling (J. Am. Chem. Soc. 2018, 140, 159. ).
Daphenylline 29 is one of a variety of related alkaloids isolated from Daphniphyllum, evergreen shrubs and trees of east and southeast Asia long used in medicinal chemistry. In the course of a second-generation synthesis of 29, a project that also led to syntheses of daphnipaxianine A and himalenine D (not illlustrated), Ang Li of the Shanghai Institute of Organic Chemistry showed that 27 could be selectively hydrogenated to 28 (Angew. Chem. Int. Ed. 2018, 57, 952. ).