Cα-substituted 4-methylpyridines have been N-lithiated and reacted with chlorotrimethylsilane and other electrophiles. The lithiated Cα-NMe2 substituted intermediate shows an interesting dichotomy of behavior towards electrophiles: It represents the borderline between compounds for which an extreme N or Cα regio-nucleophilicity is observed.
Synthesen mit<i>N</i>-Trimethylsilylheteroarylium-Salzen: Umsetzungen mit Aldehyden, Ketonen und Carbonsäuren, Reaktivitätsvergleich mit analogen<i>N</i>-Acylheteroarylium-Salzen
作者:Ernst Anders、Achim Stankowiak、Roland Riemer
DOI:10.1055/s-1987-28128
日期:——
Syntheses with N-Trimethylsilylheteroarylium Salts: Reactions with Aldehydes, Ketones and Carboxylic Acids. Comparison of Reactivity with Analoguous N-Acylheteroarylium Salts N-Trimethylsilylheterorylium salts 2 can he characterized as efficient silylating reagents for carbonyl compounds (5 or 8) and carbonic acids 11, their reactivity is comparable to that of N-acylheteroarylium salts 1. In some cases (depending on the nature of the substrates), their silylating power can be stronger than the acylating power of comparable salts 1. This will be demonstrated in the case of enolizable examples of 5and 8.
C-Sulfonylation of 4-Alkylpyridines: Formal Picolyl C–H Activation via Alkylidene Dihydropyridine Intermediates
作者:Soe L. Tun、Grant N. Shivers、F. Christopher Pigge
DOI:10.1021/acs.joc.3c00017
日期:2023.3.17
4-Picoline derivatives are converted to the corresponding aryl picolyl sulfones upon treatment with aryl sulfonyl chlorides and Et3N in the presence of catalytic DMAP. The reaction proceeds smoothly for a variety of alkyl and aryl picolines using a range of aryl sulfonyl chlorides. The reaction is believed to involve N-sulfonyl 4-alkylidene dihydropyridine intermediates and results in formal sulfonylation
在催化 DMAP 存在的情况下,用芳基磺酰氯和 Et 3 N处理后,4-甲基吡啶衍生物会转化为相应的芳基甲基吡啶砜。使用一系列芳基磺酰氯,各种烷基和芳基甲基吡啶的反应顺利进行。据信该反应涉及N-磺酰基 4-亚烷基二氢吡啶中间体,并导致未活化的甲基吡啶 C-H 键的形式磺酰化。