Alkylation

About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.

Regioselective CH Alkylation of Anisoles with Olefins Catalyzed by Cationic Half‐Sandwich Rare Earth Alkyl Complexes

Abstract: Anisole derivatives are important aromatic compounds, their structural motifs are observed in many useful materials, such as pharmaceuticals, natural products, and fluorescent dyes. The development of efficient, selective processes for the synthesis of anisole derivatives is therefore of much interest and importance. Among the most straightforward and atomeconomical routes to anisole derivatives is the C H alkylation of anisoles with alkenes. However, such C H bond alkylation approaches for the synthesis of anisole derivatives have met with limited success to date. The Friedel–Crafts reaction of anisoles with alkenes is a well-known route to alkylated anisole derivatives, but such Lewis acid catalyzed alkylation reactions generally suffer from poor regioselectivity and often give a mixture of orthoand para-regioisomers with the pararegioisomer as the main product, owing to steric and electronic influences. Recently, the late-transition-metalcatalyzed ortho-C H alkylations of various aromatic compounds possessing a directing group have been reported. However, these late-transition-metal catalysts seemed unsuitable for the ortho-selective C H alkylation of anisoles, because the interaction between an ether group and the metal center is too weak to regioselectively direct the C H bond activation. To the best of our knowledge, the catalytic ortho-selective C H alkylation of anisoles with an alkene has not been previously reported. In view of the strong oxophilicity of rare-earth metal ions and the high activity of rare-earth alkyl species toward unsaturated C C bonds, we envisioned that the rareearth alkyl complexes might serve as unique catalysts for the ortho-selective C H alkylation of anisoles with alkenes. Herein, we report the rare-earth catalyzed C H bond addition of anisoles to various olefins, which constitutes the first example of catalytic ortho-selective alkylation of an anisole compound with an alkene. We have recently found that the silylene-linked halfsandwich rare-earth alkyl complexes such as 1 (Figure 1) could serve as unique catalysts for the ortho-selective C H silylation of anisoles with hydrosilanes, because the coordination of the methoxy group to the rare-earth metal ion can direct the C H activation to selectively take place at the ortho-position. At first, we chose complex 1 as a catalyst to examine the reaction of anisole with styrene and ethylene, but no alkylation product was observed (See Table 1, entry 1). To

Alkylation of allylic derivatives. 11. Copper(I)-catalyzed cross coupling of allylic carboxylates with Grignard reagents

Abstract: Avec les reactifs alkyl Grignard, la regiochimie peut etre controlee par le choix du sel cuivreux