Wittig reactions of moderate ylides with heteroaryl substituents at the phosphorus atom
作者:Marco Ackermann、Stefan Berger
DOI:10.1016/j.tet.2005.05.002
日期:2005.7
various heteroaryl substituents at the phosphorus atom to the stereoselectivity of Wittigreactions of allylic and benzylic ylides has been studied. In the case of nitrogen bearing heteroaromatic ligands at the phosphorous atom of benzylidenephosphoranes high E-alkene selectivity's of up to 90:10 could be observed. NMR spectroscopic investigations revealed that substituents at the phosphorus have influences
Synthesis and Characterization of Alkyltris(2-pyridyl)phosphonium Salts
作者:Richard J. Bowen、Manuel A. Fernandes、Patricia W. Gitari、Marcus Layh
DOI:10.1080/10426500500328871
日期:2006.7.1
Alkytris( 2-pyridyl)phosphonium salts [(2-Py)(3)PR]X 1 [1a, R = Et, X = Br; 1b, R = Pr, X= Br; 1c, R = Bu, X = Br; 1d, R = CH2Ph, X = Br; 1e, R = CH2Ph, X = Cl] were synthesised from (2-Py)(3)P and an excess of RCl. 1c and 1e were found to rapidly decompose in hot acetone to 2,2-bipyridinium(+1) bromide 2 and (2-Py) P(O)(CH2Ph) C(OH) Me-2 3, respectively. A reaction mechanism for both products is proposed. All compounds were fully characterized, including X-ray crystallography for 1a and 3 with 1a being the first representative of this class of compounds characterized by this technique.