Synthesis of (S)- and (R)-Sporochnol by Using the Allylic Substitution of the Secondary Allylic Picolinate
摘要:
The allylic substitution of secondary allylic picolinates and copper reagents for the construction of a quaternary carbon was applied to synthesis of sporochnol. The enantiomerically enriched allylic picolinate (R)-5 was synthesized through the asymmetric hydrogen transfer of acetylene ketone 11 and the Pd-catalyzed methylation of the iodoallylic alcohol 16a. The key allylic substitution of the allylic picolinate (R)-5 with 4-MeOC6H4MgBr/Cu(acac)(2) (2:1) proceeded with 95% chirality transfer with 98% regioselectivity to afford anti S(N)2' product 6 in 89% yield, which was converted to the methyl ether of unnatural (R)-sporochnol. Similarly, the methyl ether of (S)-sporochnol (the natural form) was synthesized.
Synthesis of 6-Substituted Piperidin-3-ones via Rh(II)-Catalyzed Transannulation of <i>N</i>-Sulfonyl-1,2,3-triazoles with Electron-Rich Aromatic Nucleophiles
作者:Yang Li、Ran Zhang、Arshad Ali、Jing Zhang、Xihe Bi、Junkai Fu
DOI:10.1021/acs.orglett.7b01180
日期:2017.6.16
A highly diastereoselective rhodium(II)-catalyzed transannulation of aldehyde-tethered N-sulfonyl triazoles with electron-rich aromatic nucleophiles is reported for the first time to afford functionalized 6-substituted piperidin-3-ones. The reaction has a broad substrate scope including both aliphatic and aromatic N-sulfonyl-1,2,3-triazoles together with various aromatic nucleophiles. The addition
Asymmetric Synthesis of Dihydroindanes by Convergent Alkoxide-Directed Metallacycle-Mediated Bond Formation
作者:Stephen N. Greszler、Holly A. Reichard、Glenn C. Micalizio
DOI:10.1021/ja2105043
日期:2012.2.8
A convergent synthesis of highlysubstituted and stereodefined dihydroindanes is described from alkoxide-directed Ti-mediated cross-coupling of internal alkynes with substituted 4-hydroxy-1,6-enynes (substrates that derive from 2-directional functionalization of readily available epoxy alcohol derivatives). In addition to describing a new and highly stereoselective approach to bimolecular [2 + 2 +