Reaction with n-butyllithium

Modification of functional groups incorporated in a heterocycle is possible via ylide reactions. The 5-methylisoxazole (578) on reaction with n-butyllithium and methanesulfenyl... 

Thiophene, bromotetrahydromethyl-pyrolysis, 3, 902 Thiophene, 5-t-butyl-2-methyl-dealkylation, 4, 800 Thiophene, chloro-polymerization, 4, 758 reaction with n-butyllithium, 4, 831 synthesis, 4, 835, 882, 933 Thiophene, 2-chloromercurio-reactions... 

The nucleophilic properties of phosphorus in phosphaferrocene were demonstrated by reaction with n-butyllithium occurring at the phosphorus atom (81IC3252 820M312). 

Self-condensations are another set of important reactions of organolithium compounds. Tamao and Kawachi had reported that [(tert-butoxy diphenyl)silyl]lithium (20) exhibited ambiphUic character, and underwent a self-condensation reaction to give a [2- tert-butoxy)disilynyl]lithium derivative in THF as shown in Scheme 4, and also a nucleophilic substitution reaction with n-butyllithium . 

Alkali metals can be intercalated into MPS3 either by chemical or electrochemical techniques. Chemical intercalation takes place when the host is reacted with an organo-alkali metal compound such as n-butyllithium or sodium napthalide. The reaction with n-butyllithium can be represented as ... 

We have shown that living polydlmethylslloxanes (PDMS) can be prepared by adding the [211] cryptand to benzene solutions of D3 after reaction with n-butyllithium, at 25°C, as can be seen from the results of Table IV. The propagation reaction is much faster with [211] than with THF. 

Although tetrahydrofuran is commonly used as a solvent in organometallic chemistry, it does undergo reaction with n-butyllithium. Proton-lithium exchange at an a-position is followed by cleavage to ethylene and the enolate anion of acetaldehyde. The half-life of a-lithio-THF is 10 min at 35°C (Scheme 55) (72JOC560). 

All three isomers of butyllithium in the presence of TMEDA give very similar results for the propagation reaction. With n-butyllithium the initiation process proceeds at the same rate as propagation, but with s- and f-butyllithium the initiation is faster than propagation 173 175). In these last two cases, the process of initiation converts the very reactive secondary and tertiary carbanions into the primary ion. A similar phenomenon has been reported by Bartlett et al.176) who found that i-propyllithium in ether solution at —60° adds only a single molecule of ethylene. 

An interesting study215) of the reaction with n-butyllithium in toluene of hydrocarbons (A) and (B), respectively analogous to the cis and trans isomers of non-rigid dienes, has shown that (B), unlike (A), is unreactive ... 

Metallated thiophenes can also be readily prepared by halogen-metal exchange. Thus, 2-bromothiophene is rapidly metallated with n-butyllithium at low temperatures (e.g. -78°C) to give 2-lithiothiophene (Figure 18). This method has been shown to be applicable to the preparation of polylithiothiophenes. Thus, di-, tri- and tetra-brominated thiophenes afford the corresponding di-, tri- and tetra-lithiated thiophenes upon reaction with n-butyllithium (30 e.g. Figure 18). 

A second peculiarity of 77 expresses itself in the reaction with n-butyllithium inJ which the hydrogen atom at the phosphorus atom is displaced nucleophilically as hydride ion to give butyl-bis-2,2 -biphenylylenephosphorane (25b). Deprotonation to the phosphoranyl anion 79 occurs only to a minor extent here. For 79, an equilibrium with the ring-opened carbanionic structure 86 was proven 94,95,97). 

Alkyl-l-alkynes. Reaction of 1-bromo-l-alkynes (1) with at least 2 eq. of n-butyllithium in hexane gives 3-butyl-1-alkynes (2) in excellent yields. The favored mechanism involves metal-halogen exchange (a) and further reaction with n-butyllithium to give the dUithioalkyne (b), which is then alkylated at the propargylic carbon atom ... 

By reaction with n-butyllithium, 17 and 18 can be converted into the red syn- and anti-[2.2] (2,7)fluorenophane dianions in which the electron-rich 9-fluorenyl anions are the interacting arenes (27). A second example of such double-layered dianions, the [2.2](4,7)indenophane dianion, has been described recently (47). 

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