Organolithium addition to styrene and styrene derivatives: scope and limitations

Abstract

Styrene and a range of aryl-substituted styrene derivatives are shown to undergo efficient carbolithiation-trapping reactions in diethyl ether at Ϫ78 to Ϫ25 ЊC. The reactivities of different types of organolithium reagents were found to be: tertiary, secondary > primary; ӷ alkenyl, methyl, phenyl. Electron donating groups (e.g. methoxy and dialkylamino) at the ortho-or para-positions of the benzene ring deactivate the double bond towards organolithium addition, but their reactions with butyllithium can be facilitated by using TMEDA as co-solvent. 2-Benzyloxystyrene and 2-allyloxystyrene undergo efficient carbolithiation at Ϫ78 ЊC, but at room temperature alkyl transfer occurs, generating the corresponding alkylated phenol. 2-Vinylnaphthalene also undergoes carbolithiation-carboxylation in reasonable yield.

Lithium Choreography: Intramolecular Arylations of Carbamate‐Stabilised Carbanions and Their Mechanisms Probed by In Situ IR Spectroscopy and DFT Calculations

“…This compound presumably arises from aryl migration to give 12 followed by carbolithiation [24] of the styrenic double bond. This compound presumably arises from aryl migration to give 12 followed by carbolithiation [24] of the styrenic double bond.…”

“…To capture the initial product of rearrangement, 12 Li, without the complicating features of the second deprotonation, we replaced the cinnamyl derivative (7 c) with its a-methylated analogue 7 d. On deprotonation with sBuLi (Scheme 6), the principal isolated product 14 (23 %) contained a sec-butyl group (Table 1, entry 1). This compound presumably arises from aryl migration to give 12 followed by carbolithiation [24] of the styrenic double bond. Traces of a second product 13, formed in 6 % yield, suggested rearrangement to 12 (Scheme 5), followed by loss of the carbamate.…”

Non-Deprotonating Methodologies for Organolithium Reagents Starting from Non-Halogenated Materials. Part 2: Transmetallation and Addition to Multiple Bonds

“…This synthesis allowed the preparation of regiochemically and, in many cases, stereochemically defined 2-phenyl-1,3-cyclohexadienes 87, 1,4-dihydronaphthalenes 88 and 9,10-dihydrophenanthrenes 89 [56]. Different styrene derivatives 90 underwent efficient addition of a variety of organolithium reagents giving the corresponding adducts 91, after trapping with an electrophile, in good yields (Scheme 19) [57]. 2-Benzyloxy-and 2-allyloxystyrene gave the expected carbolithiation at low temperature, but an O-to C-transfer occurred when the reaction was warmed to room temperature.…”

Carbometallation Reactions

“…Although the anionic polymerization of styrene and its derivatives upon treatment with organolithiums is a well-known process, it was found to be solvent-dependent [90,91]. Therefore, homo-and bishomoallyllithiums, prepared by reductive lithiation of the corresponding phenyl thioethers in Et 2 O with LDMAN [92], are added to a-methylstyrene and give the corresponding cyclic product via sequential intermolecular/intramolecular carbolithiation reactions.…”

“…However, by warming the reaction mixture to room temperature before work-up, the new product 171, apparently arising by C-benzylation in the intermediate organolithium 170 by an intramolecular process, was obtained in 72 % yield (Scheme 7-102) [91].…”