4-Anisaldehyde activation

Antispasmodic activity, interestingly, is maintained even in the face of the deletion of the ethanolamine ester side chain. Reaction of anisaldehyde with potassium cyanide and dibutylamine hydrochloride affords the corresponding a-aminonitrile (72) (a functionality analogous to a cyanohydrin). Treatment with sulfuric acid hydrolyzes the nitrile to the amide to yield ambucet-amide (73). ... 

Nickelfll) complexes of p-anisaldehyde thiosemicarbazone, [Ni(HL)2X2] with X = Cl [212], Br [213], showed greater activity than the corresponding ironfll), manganesefll) and cobalt(II) complexes against Alternaria (Sp.), Paecil-omyces (Sp.) and Pestalotia (Sp.). All complexes were more active than the uncomplexed thiosemicarbazone. 

In the proposed mechanism (Scheme 5-33), both the phosphite and the aldehyde are coordinated to the catalyst before nucleophilic attack forms the P-C bond. Slow addition of the aldehyde was found to improve ees it was suggested that this minimizes unselective attack of the activated phosphite on free aldehyde instead of the desired selective attack on complexed aldehyde [26]. In related chemistry with para-anisaldehyde, Shibuya found that ees also depended on the rare earth (La, Eu, Sm) in the heterobimetallic catalyst [24]. 

After 5 minutes the cooling bath was removed and the two-phase reaction mixture was stirred at room temperature. The reaction was monitored by TLC (eluent petroleum ether-diethyl ether, 8 2). (Z)-Methyl styrene was UV active, R 0.85. The epoxide visualized withp-anisaldehyde dip stained yellow, R 0.63. 

The reaction was monitored by TLC (eluent -hcxanc diethyl ether, 9 1). ( )-Stilbene was UV active, Rf 0.82. The epoxide (UV active) stained blue with p-anisaldehyde, Rf 0.70. 

The reaction was followed by TLC (eluent dichloromethane). The starting material was UV active, stained yellow with -anisaldehyde, R 0.75. 

Silica gel (300 g) was packed to form a column of dimensions 19 cm x 6.5 cm. Elution was accomplished with hexanes ethyl acetate (19 1), both of which were used as purchased from Mallinckrodt Inc. The flow rate was 4 drops/sec. After collection of 300 mL of eluant, 20-mL fractions were collected. The pure. UV-active product (10.0 g) eluted in fractions 34-48 (R = 0.29 silica gel developed with p-anisaldehyde). Fractions 13-33 and 49-57 were combined and concentrated to give 6.9 g of material which was purified by chromatography over 200 g of silica gel to afford an additional 4.5 g of pure bromide. 

This synthetic procedure (Scheme 8) begins with an N-protected amino acid, which is converted into the corresponding oxazolidin-5-one derivative. Oxazolidin-5-one derivatives are widely used as activated amino acid derivatives for coupling and other reactions.[301 The protected amino acid 38 is reacted with p-anisaldehyde in benzene and a catalytic amount of Tos-OH to give 39 the 4-methoxyphenyl group at C2 is necessary to counteract the electron-... 

Due to a partial 77-character, aromatic carbonyl compounds have an activation energy barrier for rotation around the phenyl-carbonyl bond, the value of which is substantially increased upon protonation.44 In para-anisaldehyde a second protonation of the methoxy group will drastically decrease their barrier. The temperature-dependent NMR spectrum will reflect both exchange processes, intra- and intermolecular, as shown in Scheme 1.1. 

Addition of (C2Hs)2Zn to RCHO.1 The diol 1, prepared by Barbier addition of CsHjMgBr (2 equiv.) to the acetonide of dimethyl (R,R)-tartrate,2 converts Ti(OC2H5)4 into the optically active spirotitanate 2. In the presence of 0.05-2.0 equiv. of 2, diethylzinc reacts with anisaldehyde in toluene at 0° to form the (R)-alcohol 3 (equation I). The enantioselectivity and the chemical yield increases with an increase in 2. Surprisingly, the enantioselectivity is reversed in reactions of the... 

Not surprisingly, B(C6F5)3 is an effective catalyst for allylation of carbonyl functions. In a provocative 7. Am. Chem. Soc. communication, Maruoka and co-workers reported the chemoselective allylstannation of oTt/io-anisaldehyde in the presence of para-anisaldehyde as mediated by B(C6F5)3 (Scheme 36).263 By way of rationale, they proposed that the ortho substituted substrate is selectively activated by the LA through chelation at boron this explanation was also used to explain the high diastereoselectivity observed for X = O in the hydrostannation of PhC(0)CH(CH3)XCH3 but not for X = CH2. 

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... 

Fig. 2 Binding of 123I-labeled neutrophil-activating protein from Helicobacter pylori (HP-NAP) to derivatized NeuGca3neolactohexaosylceramide (NeuGca3Gaip4GlcNAcp3Gaip4GlcNAc P3Gaip4GlcpiCer) on thin-layer chromatograms. Glycosphingolipids detected with anisaldehyde...

The formyl group of activated aromatic aldehydes such as p-anisaldehyde is deoxy-genated on hydrogenation. The hydrogenolysis is promoted by HCl. ... 

Poly(hydroxystyrene-co-methyl methacrylate) [poly(HS-co-MMA)] can be modified to add amino groups onto the side chain of the polymer. The amine-modified polymer can react with two classes of active compounds the first class is aldehydes such as vanillin, p-hydroxybenzaldehyde, P-chlorobenzaldehyde and anisaldehyde, and the second class is phenolic esters such as p-hydroxymethylbenzoate, 2,4-dihydroxymethyl benzoate and methyl salicylate. 

Simpler iridium(I) complexes have also been observed to activate aldehydes. For instance [Tp Tr( " -C4H6)] (234) activates 4-anisaldehyde to ultimately afford the iridium(III) carbonyl complex 455 (Scheme 37). Intermediates in this process were observed spectroscopically and identified as the g g butadiene complexes 456 and 458 by performing an analogous reaction with 4-dimethylaminobenzaldehyde, for which rearrangement is less facile thus enabling the isolation of 457 and 459. It was also determined, by monitoring ( H-NMR) the reaction of 234 with 4-Me2NC6H4C( = 0)H, that the simple aldehyde adducts are intermediates in formation of the Fischer-type carbene complexes 458 and 459. 

Several other uncommon activation processes have been reported to afford carbene products, notably that of aromatic aldehydes by Tp Ir(/7" -C4H4-2,3-Me2) (234), which at 140 °C in anisaldehyde affords the carbene 458 en route to carbonyl complex 455. Though 458 cannot be isolated it has been observed spectroscopically, while the analogue derived from activation of... 

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