4-nitrobenzaldehyde dimethyl acetal

In this particular system, 4-nitrobenzaldehyde dimethyl acetal is deprotected by the acid catalyst, followed by the addition of methyl vinyl ketone (MVK) in an amine-catalyzed Baylis-Hillman reaction to give the product (Scheme 5.14). A yield of 65% for the final product was observed when the catalysts described in Scheme 5.13 were used, compared with no observed yield for the reaction with their soluble analogs. 

A similar strategy starting from 4-nitrobenzaldehyde dimethyl acetal (116) involves the subsequent aldol reaction of the obtained 4-nitrobenzaldehyde (109) with acetone for the production of p-hydroxyketone 117 (Scheme 3.33). ... 

Inspired by the application of site-isolation effects of crosslinked solid materials in so-called wolf and lamb reactions, 4-nitrobenzaldehyde dimethyl acetal has, for the first time, as electrophile been reacted with methyl vinyl ketone via a sequential add-catalyzed acetal hydrolysis followed by amine-catalyzed MBH reaction in the presence of star polymers containing core-confined PTSA analogues 153 and 4-(dialkylamino)pyridines catalysts 154 (Scheme 1.65). " ... 

The photochemical rearrangement of o-nitrobenzaldehyde or its acetals to the corresponding o-nitrosobenzoic acid derivatives has been known for many years. A careful study of the mass spectra and metastable ions obtained from methyl o-nitrosobenzoate and o-nitrobenzaldehyde dimethyl-acetal has provided strong evidence that the electron impact induced fragmentation strongly parallels the photochemical rearrangement Eq. (71). 

Other functional groups may be present in acetals or ketals prepared by these procedures. Some of these groups are keto, e.g., phenyl-glyoxal diethyl acetal carbethoxyl, e.g., ethyl acetoacetate ethylene ketal amino, e.g., /0-diethylaminopropyl methyl ketone ethylene ketal and nitro, e.g., m-nitrobenzaldehyde dimethyl acetal. In... 

The product (15-2) from aldol condensation of meto-nitrobenzaldehyde with the dimethyl acetal from ethyl 4-formylacetoacetate (15-1) provides the starting material for a dihydropyridine in which one of the methyl groups is replaced by a nitrile. Reaction of (15-2) with the eneamine from isopropyl acetoacetate gives the corresponding dihydropyridine hydrolysis of the acetal function with aqueous acid affords the aldehyde (15-3). That function is then converted to its oxime (15-4) by reaction with hydroxylamine. Treatment of that intermediate with hot acetic acid leads the oxime to dehydrate to a nitrile. There is this obtained nilvadipine (15-5) [16]. 

Commercially available Amberlite IR-120 (H -form) was used as an acid catalyst this resin is a divinylbenzene-crosslinked partially sulfonated gel-type polystyrene. As a base catalyst, PEG-PS resin-supported proline was employed. The reaction was performed in water-acetone-tetrahydrofuran (1 1 1 v/v/v) at room temperature in the presence of 20 mol. % of resin-supported proline and Amberlite. After 20 h, the reaction mixture contained the starting 4-nitro-benzaldehyde dimethyl acetal, 4-nitrobenzaldehyde and the corresponding aldol product with acetone in a ratio of 4 9 87. This means that both the... 

In contrast to the usual reaction of aromatic aldehydes with cyclic ketones o-nitrobenzaldehyde condenses with 17-ketones to produce good yields of seco-acids, a reaction which has been applied to the preparation of 16-oxa-steroids. Thus, 3 -hydroxy-5a-androstan-17-one or its acetate affords the seco-steroid (153), which can be oxidised either as the free acid by ozone and alkaline hydrogen peroxide to the diacid (155) or, as its methyl ester (154), with chromium trioxide to the monomethyl ester (156). Diborane reduction of the diacid (155) or lithium aluminium hydride reduction of the dimethyl ester (157) gave the trans-diol (158), cyclised with toluene-p-sulphonic acid to 16-oxa-androstan-3)5-ol (159) or, by oxidation with Jones reagent to the lactone (152) (as 3-ketone) in quantitative yield. This lactone could also be obtained by lithium borohydride reduction of the monomethyl ester (156), whilst diborane reduction of (156) and cyclisation of the resulting (151) afforded the isomeric lactone (150). The diacid (155) reacted with acetic anhydride to afford exclusively the cis-anhydride (161) which was reduced directly with lithium aluminium hydride to the cis-lactone (160) or, as its derived dimethyl ester (162) to the cis-diol (163) which cyclised to 16-oxa-14)5-androstan-3) -ol (164). 

Formaldehyde, the three nitrobenzaldehydes, isophthalaldehyde, and terephthaldehyde are converted into acetals by dimethyl sulfate and alkali, but 0-phthalaldehyde gives 1,3-dimethoxyphthalan under these conditions.908... 

---