Some 2-Pyridylmetallic Compounds

Abstract

The availability of 2-pyridyllithium (1) by the halogen-metal interconversion reaction expands the possibilities to other 2-pyridyl types.In a reaction between diphenyllead diiodide and 2-pyridyllithium, a mixture of organolead compounds was obtained. This mixture may be due to both disproportionation or redistribution (2) and to metal-metal interconversion reactions.Since metal-metal interconversion occurs to a lesser extent with RMgX than with RLi compounds, the 2-pyridyllithium was converted to 2-pyridylmagnesium bromide with magnesium bromide (3). This Grignard reagent then reacted smoothly with diphenyllead diiodide to give diphenyl-2-pyridyIíead iodide in 63% yield.2-CJÍ4NLÍ + MgBr2 -> AC5H4NMgBr + LiBr (C6H5)2PbI2 + AC6H4NMgBr -e (C6H6)2(C6H4N-S)PbI + MgBrI The diphenyl-2-pyridyllead iodide reacted with phenylmagnesium bromide to give triphenyl-2-pyridyllead. Interestingly enough, the 2-pyridylmagnesium bromide appeared not to react appreciably with triphenyllead iodide. Also, no metal-metal interconversion occurred at -50°between triphenyl-2-pyridyllead and n-butyllithium.The reactivity of 2-pyridyllithium relative to that of phenyllithium was of interest to other studies. One of the reagents used earlier (4) for some rate studies was benzonitrile. Its reaction rate with 2-pyridyllithium was, however, too rapid. Accordingly, p-methoxybenzonitrile was used because of its decidedly lesser activity. It was found that 2-pyridyllithium reacts much less rapidly with -methoxybenzonitrile than does phenyllithium. Interestingly, in the presence of benzene, the reaction rate with the nitrile is accelerated, probably as a result of a diluent effect by the benzene on the coordination tendencies between the RLi compound and the ethyl ether. The high yield (83-86%) of product, 2pyridyl p-methoxyphenyl ketone, shows that the interconversion reaction between 2-bromopyridine and n-butyllithium is very satisfactory and that the lower yields of some products from 2-pyridyllithium are probably due to secondary transformations.In addition to the formation of several 2-pyridylmetallic types, it was shown that 2-pyridyllithium adds to quinoline at -20°to give 2-pyridyl-2'-quinoline.

Design, Synthesis, and Biological Properties of Highly Potent Epothilone B Analogues

“…Subsequent coupling of these substrates with Me 3 SnSnMe 3 in the presence of [Pd(PPh 3 ) 4 ] in toluene at 100 °C then gave the desired products 20 a – d by reaction of the second bromide residue. The pyridyl stannanes 22 a – d were similarly synthesized from the readily available 2‐bromopyridines 21 a , b ,8 c ,5a and d ,9 respectively, through a metal–halogen exchange ( n BuLi) followed by quenching of the resulting 2‐lithio derivatives10 with n Bu 3 SnCl. Stannanes 23 11 and 24 12 were prepared from the respective halides according to the literature procedures.…”

A Nitrogen-Assisted One-Pot Heteroaryl Ketone Synthesis from Carboxylic Acids and Heteroaryl Halides

“…Among synthetic methods for heteroaryl ketones, the reactions between organometallic reagents and carboxylic acid derivatives (e.g., acid chloride, , anhydride, ester, amide, ,, or nitrile) are most widely used. Direct conversion from carboxylic acids is less frequently employed but is attractive due to its practical advantages: step/atom efficiency, commercial availability of structurally diverse carboxylic acids, and potentially reduced reaction waste.…”

“…H eteroaryl ketones are common structures in organic and medicinal chemistry, 1 particularly pyridyl ketones such as 1, 1b a potent COX-2 selective inhibitor, and 2, a key intermediate in the synthesis of TGF-β type 1 receptor inhibitor LY580276 (Figure 1). 1c,d Among synthetic methods for heteroaryl ketones, the reactions between organometallic reagents and carboxylic acid derivatives (e.g., acid chloride, 1b,2 anhydride, 3 ester, 1c amide, 1e,4,5 or nitrile 6 ) are most widely used. Direct conversion from carboxylic acids is less frequently employed but is attractive due to its practical advantages: step/atom efficiency, commercial availability of structurally diverse carboxylic acids, and potentially reduced reaction waste.…”

Reaction of 2-pyridyllithium with azine N-oxides. Simple and convenient method for the synthesis of 2,2′-bipyridine 1-oxide and 2,2′:6′,2″:6″2′″-tetrapyridine 1′-oxide

“…The product was extracted with methylene chloride, evaporated in vacuo, and crystallized from the corresponding solvent. 2,2'-Bipyridine 1-oxide (8). A.…”

“…_______ * To whom correspondence should be addressed, e-mail: rusinov@mail.ustu.ru, chupakhin@ios.uran.ru. As nucleophiles we selected 2-pyridyllithium 1 which was prepared from 2-bromopyridine and tert-butyllithium through exchange of halogen for lithium [8]. The reaction of 2-pyridyllithium with different electrophiles has been reported but there is virtually no data for the reaction with azines, including nucleophilic reactions of hydrogen substitution.…”