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On the Preparation and Determination of Configurational Stability of Chiral Thio- and Bromo[D1]methyllithiums

“…16d,21 It was found by Reich and Phillips 22 and others 23 that tin–ate complexes form in quantities detectable by NMR spectroscopy under special conditions, e.g., the presence of HMPA as additive in THF, increasing the number of phenyl substituents at tin, and low temperature (−80 °C). Furthermore, tributyltin compounds are not favorable for the formation of ate complexes, which are substantially less reactive 21 than lithium reagents. These facts induce us to think that tin–ate complexes play only a minor role here, if at all, and that salt free species of heteroatom-substituted methyllithiums are produced.…”

“…In analogy to previous results, we assume tin–lithium exchange whenever used here in this paper to generate heteroatom-substituted methyllithiums to follow a retentive course. 16d,21 It was found by Reich and Phillips 22 and others 23 that tin–ate complexes form in quantities detectable by NMR spectroscopy under special conditions, e.g., the presence of HMPA as additive in THF, increasing the number of phenyl substituents at tin, and low temperature (−80 °C). Furthermore, tributyltin compounds are not favorable for the formation of ate complexes, which are substantially less reactive 21 than lithium reagents.…”

Asymmetric Deprotonation with Alkyllithium–(−)‐Sparteine

“…Only few types of benzyllithium compounds being configurationally stable in solution at −78 • C are known: lithium-TMEDA complexes of secondary O-benzyl N,N-dialkyl carbamates, such as 211 159 or the 2,4,6-triisopropylbenzoate 212 160,161 , of secondary Naryl-N-Boc-benzylamines (213) and the dilithio-(−)-sparteine derivative 214 162 .…”

“…Inversion of the configuration to form ent-218 is only observed with chloro-stannanes. Similar results were found by Hammerschmidt and coworkers for the stannylation of the triisopropylbenzoate 219 161 . From these investigations, the absolute configuration of a tin derivative was elucidated by X-ray crystal structure analysis 161 .…”

Highly Diastereoselective Deuteration of 2-p-Tolylsulfinyl Ethylbenzene at Benzylic Position

“…This inversion was demonstrated by Sn-Li exchange experiments because of the transmetallation and deuteration (or protonation) processes with retention of configuration. 2 …”