Ortho- Alkylations, carbon-hydrogen bonds

Described in this section is a convenient synthetic procedure for preparation of RuH2(CO)(PPh3)3,[3 61 which is a highly effective catalyst for the conversion of carbon-hydrogen bonds to carbon-carbon bonds, and typical procedures for RuH2-(CO)(PPh3)3-catalysed reactions of aromatic ketones with olefins/2 3 71 acetylenes/41 and arylboronates/51 giving ortho alkylation, alkenylation, and arylation products, respectively. [Pg.14]

The use of transition metal catalysts to effect alkylations, alkenylations, arylations, and acylations in pyridines has been reviewed, and there has been a computational study of the ortho-alkylation of pyridine by scandium-catalysed reactions with alkenes. DFT calculations indicate that the stability of the developing metal-aryl bonds may be important in determining regioselectivity in palladium-acetate-catalysed carbon-hydrogen substitution in heteroarenes. ... [Pg.239]

Hydrogen attached to ring carbon atoms of neutral azines, and especially azinium cations, is acidic and can be replaced by a metal formally being removed as a proton. Alkyllithiums can be used as bases for this purpose however, the reaction can be accompanied by addition of the alkyl anion to the ring C=N bond. To avoid this, sterically hindered bases with strong basicity but low nucleophilicity can be utilized. Among these are lithium tetramethylpiperidide (LiTMP) and lithium diisopropylamide (LDA). If the anion contains an ortho halogen atom, then this can be eliminated to form a pyridyne (see Section 3.2.3.10.1). [Pg.297]

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