3,5-Dimethoxybenzaldehyde

A 250-mL, round-bottomed flask equipped with a magnetic stirring bar is charged with 2 (1.71 g, 2.0 mmol) and pyridine hydrochloride (100 g) ( Caution. Pyridine hydrochloride is toxic with a disagreeable order.). The flask is fitted with a short, Vigreux condenser and a heating mantle is used to 

For a review of biomimetic systems that are derived from 5,10,15,20-tetrakis(2-amino-phenyl)-21H,23H-porphine see (a) B. Morgan and D. Dolphin, Structure and Bonding, 64, 115 (1987). For biomimetic systems that are derived from 5,10,15,20-tetrakis(2,6-di-aminophenyl)-21H,23H-porphine see (b) C. A. Quintana, R. A. Assink, and J. A. Shelnutt, Inorg. Chem., 28, 3421 (1989) and (c) C. M. Drain and B. B. Corden, Inorg. Chem., 28,4374 (1989). 

Tsuchida et al. have prepared 3 from 1 in 9.3% overall yield by a different procedure. See E. Tsuchida, T. Komatsu, E. Hasegawa, and H. Nishide, J. Chem. Soc., Dalton Trans., 2713 (1990). 

SUBMITTED BY DON SOLOOKI, JOSEPH D. FERRARA,5 DENNIS MALABA, JOHN D. BRADSHAW, CLAIRE A. TESSIER, and WILEY J. YOUNGS  

5 Present address Molecular Structure Corp., 3200 Research Forest Drive, The Woodlands, TX 77381-4238. 

Unless otherwise stated, all manipulations are carried out under an atmosphere of argon using standard Schlenk techniques. The glassware used in the preparation of (2-iodophenyl)acetylene and the Stephens-Castro coupling of copper acetylide is dried in an oven at 140°C overnight. Potassium tert-butoxide (Aldrich) is sublimed at 150°C on a diffusion-pump vacuum 

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Fig. 4.3 I solated yields of Biginelli dihydropyrimidine products (Scheme 4.24 a) in different reaction vessels of a 36 vessel rotor (Fig. 3.7). Outer ring, vessels 1-20 inner ring, vessels 21-36). Aldehydes a, benzaldehyde b, 2-hydroxybenzaldehyde c, 3,4-dimethoxybenzaldehyde d, 3-nitrobenzaldehyde e, 2-chlorobenzaldehyde f, 4-(N,N-dimethylamino)benzaldehyde. Adapted from [85],...

Bromo-3,4-dimethoxybenzaldehyde cyclohexyl 1 mine Cyclohexanamine, N-[(2-bromo-4,b-dimethoxyphenylJmethylene]- (73252-55-8), 65, 10B BROMOMETHANESULFONYL BROMIDE METHANESULFONYL BROMIDE, BR0M0- ... 

Iodo-3,4-dimethoxybenzaldehyde cyclohexy11mine Cyclohexanamlne, N-[(2-1odo-4,5-dimethoxyphenyl)methylene]- (61599-78-8), 65, 108... 

SYNTHESIS A solution r > 3,4-dimethoxybenzaldehyde in 140 mL acetic acid was treated with 23 mLi. uethane and 12.5 g anhydrous ammonium acetate,... 

SYNTHESIS A solution of 166 g 3,4-dimethoxybenzaldehyde in 600 mL acetic acid was well stirred, and brought up to an internal temperature of exactly 25 °C. There was added, in very small portions, a 40% solution of peracetic acid in acetic acid. The evolved heat was removed with an external ice bath, and the rate of addition was dictated by the requirement that the internal temperature should not exceed 25 °C. A total of 210 g of the 40% peracetic acid was used. The reaction mixture was poured into 3 L H2Q. and the acetic acid neutralized by the addition of solid K2C03. The neutral aqueousphase was extracted with 5x150 mL Et,0, and the... 

An alternative procedure49 for effecting the conversion of acid chlorides into aldehydes is chemical reduction with bis(triphenylphosphine)copper(i) tetrahy-droborate (see also Section 5.7.4, p. 594). The procedure is illustrated by the synthesis of 3,4-dimethoxybenzaldehyde which is isolated as the 2,4-dinitro-phenylhydrazine derivative50 (cognate preparation in Expt 6.120). 

Cognate preparation. 3,4-Dimethoxybenzaldehyde 2.4-dudtrophenylhydror zone (use of bis(triphenylphosphine)copper(i) tetrahydroborate)50 3,4-Dimethoxybenzoyl chloride (1.14g, 5.7 mmol) in acetone (100 ml) is treated with triphenylphosphine (3.04 g, 11.6 mmol). To this solution at room temperature, bis(triphenylphosphine)copper(i) tetrahydroborate (3.47 g, 5.8 mmol) (Section 4.2.49, p. 449) is added and the reaction mixture stirred for 45 minutes. The white precipitate of triphenylphosphine copper chloride (4.9 g, 5.5 mmol) is removed by filtration and the filtrate evaporated to dryness. The residue is extracted with ether (the ether-insoluble residue is shown to be triphenylphosphine borane). The ether is removed, the residue... 

Bromo-3,4-dimethoxybenzaldehyde was purchased from the Aldrich Chemical Company, Inc. (Milwaukee) or readily prepared by bromination of veratraldehyde (Aldrich Chemical Company, Inc. or Tokyo Kasei).4... 

A. 6-Bramo-S,4-dimethoxybenzaldehyde cyclohexylimine (1). A 2-L, threenecked flask is equipped with a Dean-Stark trap, reflux condenser, magnetic stirrer, and nitrogen inlet. The vessel is purged with nitrogen and charged with 40,0 g (0.16 mol) of 6-bromo-3,4-dimethoxybenzaldehyde (6-bromo-veratraldehyde) (Note 1), 22.4 mL (0.20 mol) of cyclohexylamine (Note 2), and 800 nt of toluene. The mixture is refluxed for 16 hr (Note 3). The solution is cooled to room temperature and the solvent is removed on a rotary evaporator. The residual crystalline mass is recrystallized from a 3 1 hexane-methylene chloride mixture (1.5 L) to provide 48.4-51.4 g of the imlne 1 as white crystals In two crops (mp 172-172.5°C)2 (Note 4). 

A study by Hayashi et al. demonstrates that less reactive electron-rich aromatic aldehydes efficiently undergo Mannich reactions under high pressure induced by water freezing [8], For instance, in the Mannich reaction of p-anisaldehyde, 3,4-dimethoxybenzaldehyde or N-acetyl-(4-formyl)aniline, with acetone and p-anisidine, good yields (61-99%) and excellent enantioselectivities (92-97%) have been obtained under water-freezing high-pressure conditions while there is no reaction at room temperature at 0.1 MPa (Scheme 9.6). 

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