CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XI. ω-(p-PHENYLTHIO)-p-SUBSTITUTED ACETOPHENONES

Abstract

The analysis of the vco bands in the I.R. spectra of o-(p-pheny1thio)psubstituted acetophenones indicates the presence of cislguuche rotational isomerism. The decreasing cislguuche ratio on going from electron-attracting to electron-donating substituents at the phenylthio group in each p-substituted acetophenone series is discussed in terms of the ~*~~/ u~.~ hyperconjugative interaction in the gauche rotamers. The carbonyl cis shifts (Av,) of the title compounds are interpreted as due to an interplay of Field (F) and Inductive (I) Effects. The carbonyl gauche shifts (Av,) trend in the whole series has been ascribed to the variation of the extension of the T *~~/ U~. , hyperconjugative interaction. The lower Non-Additivity Effect (NAE) of the methylene carbon of the title compounds in relation to the corresponding w-bromo and w-iodo acetophenones together with the lowest NAE of the methylene carbon for the o-(p-nitropheny1thio)-p-nitroacetophenone (3) suggests the simultaneous occurrence of the T * ,~/ U~.~ and ~~~l u *~.~ orbital interactions. The U.V. spectra of the w-thiosubstituted acetophenones ,display a n + w*co band which is bathochromically shifted in relation to the corresponding acetophenones except for compound (3) where this band is hypsochromically shifted. This behavior has been ascribed mainly to the T *~~/ ( T *~.~ hyperconjugative interaction in the excited state.

CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XV. α-(ARYLSULFINYL)-p-SUBSTITUTED ACETOPHENONES

“…These NAE values are still lower than those for the o-iodoacetophenones26 whose (A6) mean value is -15.0 ppm. This behavior is similar to that previously observed for the a-arylthioacetophenones, 6 and also suggests a decreasing contribution of the n*cdoc-so interaction for the gauche rotamers of the a-arylsulfinylacetophenones 1-8, due to the simultaneous occurrence of the ncdo*C-SO orbital interaction, which leads to a decrease in the NAE values.…”

Preferred conformations in the solid state of some α-(p-phenylsulfinyl)-p-substituted acetophenones

“…2.1. Synthesis, NMR and CHN analyses -(p-Phenylsul®nyl)-p-substituted acetophenones XÐ PhC(O)CH 2 S(O)PhÐY [(1)±(3)] were prepared by the following procedure: to a solution of the correseponding -(pphenylthio)-p-substituted acetophenone (Olivato & Guerrero, 1992) in acetic acid, cooled to 273 K, was added dropwise an equivalent amount of 30% hydrogen peroxide. The stirred reaction mixture was kept at room temperature until all the ketosul®de had reacted.…”

Análise conformacional das α-etilsulfinil- e α-etilsulfonil-acetofenonas-para-substituídas; α-metiltio, α-dietoxifosforilacetofenonas-para-substituídas e suas formas mono- e di-oxigenadas

“…10 Método Geral empregado na preparação das a-metilsulfonila-dietoxifosforilacetofenonas-para-substituídas lI!. 5 4 Preparação da a-bromo-para=bromoacetofenona l1I 6. 1.…”

“…Preparou-se uma solução a partir de 3,°g (12,8 mmols) Ponto de fusão = 136 -138°C. Partindo de 5,00 g (0,025 moI) de metiltiometilfosfonato de dietila em 100 roL de THF e adicionando 25,2 roL (0,038 moI) de n-butilítio (1,5 M), 3,82 g (5,3 roL, 0,038 moI) de düsopropilamina e 4,41 g (3,2 roL, 0,025 moI) de cloreto de para-cloro-benzoíla obteve-se 5,91 g (70%) de a-metiltio-a-dietoxifosforil-para-cloroacetofenona (sólido branco).…”