Benzaldehyde structure

Harman and brevicarine, C17H21N3 (mp 104°) B-2HC1 (mp 189°). The latter is an indole derivative (27). Brevicolline on dehydrogenation with selenium yields a number of products containing the indole nucleus. A reactive methyl group is indicated by the fact that the alkaloid condenses with benzaldehyde. Structure XI is tentatively suggested (28, 29). 

The same products can be also obtained from 267 and benzaldehyde. This behavior indicates the presence of an active methylene group and supports the thiazolone structure (267a). Alkyl or aryl ethers of 267 are prepared by two different procedures (Scheme 139). 

Because the carbon atom attached to the ring is positively polarized a carbonyl group behaves m much the same way as a trifluoromethyl group and destabilizes all the cyclo hexadienyl cation intermediates m electrophilic aromatic substitution reactions Attack at any nng position m benzaldehyde is slower than attack m benzene The intermediates for ortho and para substitution are particularly unstable because each has a resonance structure m which there is a positive charge on the carbon that bears the electron withdrawing substituent The intermediate for meta substitution avoids this unfavorable juxtaposition of positive charges is not as unstable and gives rise to most of the product... 

Reaction of benzaldehyde with 1 2 octanediol in benzene containing a small amount of p toluenesulfonic acid yields almost equal quantities of two products in a combined yield of 94% Both products have the molecular formula C15H22O2 Suggest reasonable structures for these products... 

Arnygdabn a substance present in peach plum and almond pits is a denvative of the R enantiomer of benzaldehyde cyanohydrin Give the structure of (/ ) benzaldehyde cyanohydrin... 

When partially resolved samples of 5-hydroxymethylpyrrolidin-2-one are allowed to react with benzaldehyde in the presence of an acid catalyst, two products, A (C12H13NO2) and B (C24H26N2O4), are formed. The ration A B depends on the enantiomeric purity of the starting material. When the starting material is optically pure, only A is formed. When it is racemic, only B is formed. Partially resolved material gives both A and B. The more nearly it is enantiomerically pure, the less B is formed. The products A is optically active but B is achiral. Develop an explanation for these observations, including structures for A and B. 

More serious limitations and precautions apply to compounds in which not all three R, R, and R" groups are aromatic. Autocondensation of benzylideneacetone (111) yields an unstable chloroferrate which may be 113 or 115, according to whether a Michael addition to 112 or a crotonic condensation to 114 is first involved. Since compound 113 could readily be prepared from 2,6-dimethyl-4-phenylpyrylium and benzaldehyde, the structure of the reaction product should be easily soluble. Another equivocal product is formed from two moles of benzylideneacetone, but a definite structure (116) results from chalcone and benzylideneacetone. ... 

The triazole 76, which is more accurately portrayed as the nucleophilic carbene structure 76a, acts as a formyl anion equivalent by reaction with alkyl halides and subsequent reductive cleavage to give aldehydes as shown (75TL1889). The benzoin reaction may be considered as resulting in the net addition of a benzoyl anion to a benzaldehyde, and the chiral triazolium salt 77 has been reported to be an efficient asymmetric catalyst for this, giving the products (/ )-ArCH(OH)COAr, in up to 86% e.e. (96HCA1217). In the closely related intramolecular Stetter reaction e.e.s of up to 74% were obtained (96HCA1899). 

The UV and IR spectra eliminate structures with a CN double bond. The isomerism of nitrones and oxaziranes thus cannot be a result of CIS or traris arrangement of substituents about a double bond. The carbon atoms of an oxazirane are still at the oxidation level of the carbonyl compound used in its syntheses. By acid hydrolysis, for example, 2-terf-butyl-3-phenyloxazirane (9) can be split into benzaldehyde and tert-butylhydroxylamine fEq. (8)]. ... 

Thus the structure of the oxazirane must formally involve elimination of water from one molecule each of the carbonyl compound and of an alkyl hydroxylamine. (In the synthesis of oxazirane from N-methylhydroxylamine-O-sulfonic acid and benzaldehyde, this method... 

The structures along the reaction path in Fig. 8.13 are outlined in Fig. 8.14 starting with benzaldehyde activated by (MeO)2AlMe in the reaction with Danishefsky s diene 10 leading to the transition-state structure for the formation of the al-dol-like intermediate, and finally the formation of the hetero-Diels-Alder adduct. 

To the conditions enunciated by Mehrling and Welde might be added that the side chain must be unsaturated since di-hydroionone only has a faint odour, and also that the violet odour is occasiopally present with bodies of quite different structure from the ionones, for instance A 2 2 4 tri-methyl-tetra-hydro-benzaldehyde. 

Benzyl bromide is converted into benzaldehyde by heating in dimethyl sulfoxide. Propose a structure for the intermediate, and show the mechanisms of the two steps in the reaction. 

The aldehyde structures and the tosylhydrazone salts were varied in an extensive study of scope and limitations, with use of both achiral and chiral sulfur ylides [73]. Aromatic aldehydes were excellent substrates in the reaction with benzaldehyde-derived ylides, whereas aliphatic aldehydes gave moderate yields and transxis ratios. 

Miscellaneous Identified Inhibitors. 3-Acetyl-6-methoxy-benzaldehyde is present in the leaves of the desert shrub Encelia farinosa. It is apparently leached from the leaves and washed into the soil by rain. Concentrations of approximately 0.5 mg. per gram of dried leaf material have been measured. In sand culture studies, growth of tomato seedlings was inhibited by 50 p.p.m. while 115 p.p.m. reduced growth by 50% (53). A concentration of 250 p.p.m. killed the test plants within one day. The structure was confirmed by synthesis, and the synthetic material was shown to be as active as the natural product (54). Derivatives were also prepared in which a cyano, nitro, or amino group was substituted for the aldehyde moiety. The amino derivative was reported to be the most highly toxic. 

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