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GeneralMelting points were determined on Büchi Melting Point B-540. NMR spectra were recorded on a JEOL ECX 400 spectrometer. Tetramethylsilane ( = 0) was used as an internal standard for 1 H NMR and CDCl 3 ( = 77.0) for 13 C NMR. Mass analysis were performed on a Agilent G1969 LC/MDS TOF. IR spectra were recorded on a NICOLET 380 FT-IR. Elemental analyses were performed on a J Science Lab. micro corder JM-10. Preparation of NaHSO 4 /SiO 2SiO 2 [Wakogel C-200 (Wako Pure Chemical Ind. Ltd.), 10 g] was added to a solution of NaHSO 4 ·H 2 O (30 mmol, 4.14 g) in distilled water, and the mixture was stirred at room temperature for 0.5 h. The water was removed by rotary evaporator under reduced pressure, and the resulting reagent was dried in vacuo (10 mmHg) at 120 °C for 5 h. Typical procedureA mixture of -diketones 1 (6 mmol), o-hydroxybenzyl alcohols 2 (2 mmol) and NaHSO 4 /SiO 2 (2.1 mmol, 1.0 g) in dichloroethane (10 mL) was stirred at 80 °C for 5 h, and then the used supported reagent was removed by filtration. The filtrate was evaporated to leave crude product, which was purified by column chromatography (hexane/ethyl acetate) to obtain 3.

Simple and efficient methods were developed for sp 2-sp 3 and sp 3-sp 3 CC bond-activation reactions of 2-substituted 1,3-diketones. 3-Substituted 3-bromopentane-2,4-diones were deacylated in the presence of an aromatic compound and a silica gel supported Brønsted acid containing sulfonic groups. The carbocation formed by cleavage of the sp 3-sp 3 CC bond of the dione alkylated the aromatic compound.

A novel and efficient method for the activation of the C(sp 3 )-C(sp 3 ) bond was developed. The C(sp 3 )-C(sp 3 ) bond in 3-benzhydryl pentane-2,4-dione was easily cleaved in the presence of NaHSO 4 /SiO 2 to form benzhydryl cation which reacted with aromatic compounds at 110 °C for five to six hours to afford triarylmethanes in good yields. This reaction using Brønsted acids was applicable for the alkylation of electron-rich aromatics containing alkyl halides as a side chain.