Synthesis of Hemilabile P,N Ligands: ω-2-Pyridyl-n-alkylphosphines
作者:Achim Jansen、Stephan Pitter
DOI:10.1007/pl00010260
日期:1999.6
A series of P,N ligands of the general formula (2-py)-(CH2)(n)-PR2 (2-py: 2-pyridyl; R: i-Pr (n = 1, 4-7), Ph (n = 5-7)) 4a-g and 6a has been synthesized. Starting from 2-picoline (1), 2-(omega-chloroalkyl)pyridines 3a-d are prepared. The reactions of 3a-d with (i-Pr)(2)PLi and Ph2PLi, respectively, result in the title compounds 4a-g in up to 89% yield. Reaction of Cl-(CH2)(3)-P(i-Pr)(2) with 2-picolyllithium (2) is an alternative route to 4a. Additionally, P,P,N ligands 7a and 9 are synthesized by similar methods. All new compounds were fully characterized. The formation of cyclic pyridinium derivatives 5a and 5b from intramolecular SN reactions of 3a and 3b is discussed in detail.
Photocyclization Reactions of Cyclohexa- and Cyclopenta-Fused Pyridinium Salts. Factors Governing Regioselectivity
作者:Zhiming Zhao、Eileen Duesler、Canhui Wang、Hua Guo、Patrick S. Mariano
DOI:10.1021/jo051348l
日期:2005.10.1
The results of studies described in this report show that irradiation of 1,2-cyclopenta-fused pyridinium perchlorate in aqueous base promotes a remarkably regioselective photocyclization reaction that results in exclusive formation of a single tricyclic allylic alcohol. Moreover, transformation of this photoproduct to a spirocyclic amido diester followed by enzymatic desymmetrization produces an enantiomerically