Samarium-mediated intramolecular cross-couplings of an α,β-unsaturated N-acylpyrrole
作者:Katherine R. Law、Christopher S.P. McErlean
DOI:10.1016/j.tetlet.2016.06.010
日期:2016.7
The first example of an α,β-unsaturated N-acylpyrrole undergoing a SmI2-mediated cyclization is reported. In contrast to other unsaturated units, the intermediate samarium enolate readily engages in aldol-type reactions, necessitating careful control of the reaction conditions.
The stereoselectivesynthesis of the WXYZA'-ring system of maitotoxin has been accomplished via a linear synthetic approach, in which key reactions were SmI 2-induced cyclization of beta-alkoxyacrylate for the construction of the A'-, Y-, and X-rings and 6- endo cyclization of hydroxy vinylepoxide for that of the Z- and W-rings.
Convergent Synthesis of the ABCDEF-Ring System of Yessotoxin and Adriatoxin
作者:Keisuke Suzuki、Tadashi Nakata
DOI:10.1021/ol026804w
日期:2002.10.1
[GRAPHICS]The convergent synthesis of the ABCDEF-ring system of yessotoxin and adriatoxin was accomplished. This efficient convergent strategy was performed on the basis of the coupling of the acetylide of the A-ring and the triflate of the DEF-ring, oxidation of the alkyne to diketone, intramolecular diacetalization, and stereoselective reduction of the diacetal with Et3SiH-TMSOTf.
Synthesis of 2-Methylenetetrahydropyran-3-ol Derivative, a Key Segment for Convergent Synthesis of Polycyclic Ethers Based on Suzuki-Miyaura Coupling
2-Methylenetetrahydropyran-3-ol derivative, a key segment for convergent synthesis of polycyclic ethers based on Suzuki-Miyaura coupling, was efficiently synthesized by two methods; (1) via SmI2-induced reductive cyclization of beta-alkoxyvinyl sulfone with aldehyde followed by elimination of the sulforyl group, and (2) via SmI2-induced cyclization of beta-alkoxyvinyl sulfoxide with aldehyde followed by dehydration of the 2-hydroxymethyl group.
Five-, four-, and three-membered carbocyclic rings from 2-deoxyribose by intramolecular nucleophilic displacement reaction
作者:Karsten Krohn、Guido Boerner
DOI:10.1021/jo00021a015
日期:1991.10
1,3-Dithianes such as 4, 9, 11, 13, and 19 derived from 2-deoxy-D-ribose (1) undergo intramolecular displacement reactions to give three-, four-, and five-membered carbocyclic rings (5, 10, 12, 15, and 20). Cyclopropanes are favored over the cyclobutanes when starting from the epoxides 9 or 11. Treatment of the tosylate 19 gives only a small yield of the corresponding cyclobutane 20, the major product being the ketone 21.