53966-53-3Relevant articles and documents
Sequestered alkyllithiums: Why phenyllithium alone is suitable for betaine-ylide generation
Wang, Qian,Deredas, Dariusz,Huynh, Cyril,Schlosser, Manfred
, p. 570 - 574 (2007/10/03)
The key step in the trans-selective modification of the Wittig reaction is the α-lithiation of the lithium bromide coordinated ylide - aldehyde adduct (the so-called "P-betaine"). Only phenyllithium effects this deprotonation rapidly and cleanly. Alkyllithiums (in particular, butyl-, sec-butyl-, and tert-butyllithium) react only sluggishly and incompletely, being tied up in very stable mixed aggregates with the lithium alkoxide part of the betaines.