Conformational analysis of ortho and meta-acetophenones α phosphonates and their derivatives substituted: α methylthio; α methylsulphinyl: and α methylsulphonyl and reactivity study of substituted ortho and meta α haloacetophenones with triethylphosphite / Análise conformacional de orto e meta-acetofenonas α -fosfonatos e seus derivados: α-metiltio; α:metilsulfinil; e α-metilsulfonil- substituídas e estudo da reatividade de α-haloacetofenonas orto e meta-substituídas com trietilfosfito

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

This thesis reports the study of the reactivity of the competitive Michaelis- Arbuzov and Perkow reactions of some orto- and meta- substituted α-haloacetophenones (I) [o- and m-Y-Φ-C(O)CH2-Hal] (Hal = CI, Br e I; Y = OMe, Me, H, F, CI, Br and NO2) with triethyl phosphite, by gas chromatography, and the conformational analysis of some orto- and meta-substituted α-heteroacetophenones (II) [o- and m-Y-Φ-C(O)CH[X]-P(O)(OEt)2] (X = H, SMe, S(O)Me and SO2Me; Y = OMe, Me, H, F, Cl, Br and NO2), by means of infrared spectroscopy and ab initio HF/6-31 G** computations. For reactions involving meta-substituted α-bromoacetophenones and triethylphosphite it was found a good correlation between the ketophosphonate / enolphosphate ratio (K/E) and the σm constant. The (K/E) ratios obtained from the reaction of the orto- substituted α-chloro- and α-iodo-acetophenones and triethylphosphite did not show a clear trend with any substituent constant. However, a good correlation between the (K/E) ratio and the σI constant was obtained in the case of the reaction involving the orto-substituted α-bromoacetophenones and triethylphosphite. The vco infrared analysis in general compares well with the ab initio calculations which showed the occurrence of one or two stable conformations for compounds of series (II), being the gauche (syn-clinal) the most stable and the cis (syn-periplanar) or the gauche (anti-clinal) the second one. The vco IR analysis of the orto-substituted α-methylthio-α-diethoxyphosphorylacetophenone series was precluded due to its strong enolization. As for the meta-substituted α-methylsulfinyl-α-diethoxyphosphoryl-acetophenones the IR and NMR spectroscopies along with the ab initio computations showed the ocurrence of a diastereomeric equilibrium both in gas and in solution.

ASSUNTO(S)

spectroscopy conformational analysis acetophenones theoretical calculations reações orgânicas análise conformacional espectroscopia fosfonatos acetofenonas cálculos teóricos compostos alicíclicos phosphonates

ACESSO AO ARTIGO

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