O-Anisaldehyde

ALDEHYDES FROM 4,4DIMETHYL2 0XAZ0LINE AND GRIGNARD REAGENTS o-ANISALDEHYDE... 

If this step is omitted, the o-anisaldehyde obtained after hydrolysis of the oxazolidine is contaminated with 5-10% o-bromoanisole. 

ALDEHYDES FROM 4,4-DIMETHYL-2-. OXAZOLINE AND GRIGNARD REA-j GENTS O-ANISALDEHYDE, 54,... 

In a 1-1., round-bottomed flask is placed 72 g. of the crude oxazolidine in 600 ml. of water, and 201.6 g. (1.6 moles) of hydrated oxalic acid is added. The mixture is then heated under reflux for 1 hour, cooled, treated with 600 ml. of water to dissolve precipitated oxalic acid, and extracted with three 100-ml. portions of ether. The combined ethereal extracts are washed with 50 ml. saturated sodium bicarbonate solution and then dried over anhydrous potassium carbonate. Concentration of the ethereal solution gives 30-35 g. of crude aldehyde. Distillation of this material at 70-75° (1.5 mm.) gives pure o-anisaldehyde (22.8—26.3 g. 51-59%), m.p. 35.5-38° (Note 9). 

Carbonyl alkylation and condensation reactions are always of great value in synthesis, and the formation of o-ANISALDEHYDE via 4,4-dimethyl-2-oxazoline, 2,2-DIMETHYL-3-PHENYLPROPION-ALDEHYDE via alkylation of the magnesio-enamine salt and threo-4-HYDROXY-3-PHENYL-2-HEPTANONE via a directed aldol... 

Metalation of 3-ethoxypyridine (294) followed by condensation with o-anisaldehyde affords 393 which, upon oxidation and cyclization, gives the 1-azaxanthone 394 (Scheme 121) (84TH1). 

The freshly ground lithium enolate 1 (1.2 equiv.) was mixed with o-anisaldehyde 2a (1 equiv.) in argon atmosphere at room temperature. The reaction was allowed to continue at room temperature under vacuum for three days, quenched with aqueous NH4CI and the mixture extracted with three portions of diethyl ether. The combined organic extract was washed with water and dried with anhydrous Na2S()4- The solvent was removed using a rotary evaporator at reduced pressure to yield the crude product. The crude product was found to contain mainly anti aldol product (syn/anti ratio 8 92). Further purification was earned out using preparative TLC with methanol-benzene (5 95 in volume) as eluent. The purified product thus isolated was a colorless solid (mp 64-65 °C, yield 70%) with the same syn/anti ratio as that of the crude product. 

Kinetic resolution of ( )-(o-anisaldehyde)Cr(CO)s (1).1 This arenechromium carbonyl has been resolved by chromatography of a derivative, but a more convenient method involves reaction with L-valinol to form two imines (a, b) with widely different Rf values. The fastest moving fraction (a) is a precursor to (-)-l, whereas the slower moving fraction provides ( + )-l on hydrolysis. 

Aniline, 4,4 -azodi-, 40,18 Aniline, reaction with hexachloroace-tone to form a,reaction with maleic anhydride, 41,94 o-Anisaldehyde, 44, 4 Anisoin, reduction to deoxyanisoin by tin and hydrochloric add, 40, 16 Anthracene, chlorination by cupric chloride, 43,15... 

Recently, catalytic amounts of Lewis acids have been used in the reaction of allyllic tri- -butyltins with carbonyl compounds. Maruoka et al. report the remarkably chemoselective allylstannation of o-anisaldehyde over/>-anisaldehyde, catalyzed by BlCgFsL.1 z Piers et al. report that the chemoselectivity observed does not rely on classical chelation control. They conclude that stannylium ion pair [Bu3Sn(o-anisaldehyde)2]+[o-ArCH(allyl)OB(G6Fs)3] is the active species which is preferentially formed over the complex of/>-anisaldehyde with BlCgFsL (Equation (44)).143 Lambert et al. report a similar formation of stannyl cation from allyltri- -butyltin and trityl (CgFsLB-.144... 

In the field of arene tricarbonyl chromium complexes, racemic aldehydes can be resolved quantitatively by chromatographic separation of the corresponding semioxamazones. The first optical resolution was carried out on the semioxamazone made from the chromium tricarbonyl complex of o-anisaldehyde. - The separation of the diastereomers was done by silica gel... 

Columbia. The preparation of the reagent from 2-amino-2-methyl-l-propanol and formic acid is described in a note to a procedure for the synthesis of o-anisaldehyde ... 

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