2-Styryl-4H-1,3-benzoxazin-4-onium salts

A method was developed for the synthesis of 2-styryl-4H-1,3-benzoxazin-4-onium salts by condensation of 2-alkylbenzoxazinonium salts with aromatic aldehydes. It is shown that these same compounds are formed by acid condensation of salicylamides, salicylnitrile, or salicylaldoxime with aromatic aldehydes in acetic anhydride. The hydrolysis and alcoholysis of the synthesized salts were studied.     

Oxidation of 1-(4-nitrophenyl)-2-formylpyrrole

Pyrrole aldehydes interact with oxidizing agents to yield products which are oxidized to different degrees. Pyrrolecarboxylic acids are formed under the influence of silver oxides, an alkaline solution of permanganate, and 2–10% sulfuric acid [1–3]. With peroxidation of hydrogen, 5-unsubstituted pyrrole aldehydes convert to pyrrolone [4], and pyrrol-2-aldehyde converts to succinimide [5]. Chromacetate and chromium sulfuric acids oxidize pyrrole aldehydes to maleinimides [3].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 495–499, April, 1982.     

Reaction of Zinc Enolates of Alkyl Esters of Substituted 4-Bromo-3-Oxoalkanoic Acids with Aldehydes

Zinc enolates formed from ethyl 4-bromo-2,2,4-trimethyl-3-oxopentanoate react under the conditions of one- of two-stage synthesis with aliphatic, unsaturated, or aromatic aldehydes to form 6-R-2,2,4,4-tetramethyl-2,3,5,6-tetrahydropyran-2,4-diones. Zinc enolates obtained from ethyl 4-bromo-2,2-dimethyl-3-oxopentanoate, -hexanoate, and -2,2,5-trimethyl-3-oxohexanoate under the similar conditions react with aliphatic or aromatic aldehydes to give mainly 5-R¹-6-R²-3,3-dimethyl-2,3,5,6-tetrahydropyran-2,4-diones as E or Z isomers or their mixtures. Zinc enolates generated from the ethyl 4-bromo-2,2-diethyl- or 2-benzyl-2-ethyl-3-oxobutanoates react with aromatic aldehydes to give ethyl 5-R-2-R-2-ethyl-3-oxo-4-pentenoates as E isomers.     

A Novel Nitrone Cycloaddition/Rearrangement

Adamantanone-derived nitrone 4 and some other keto-nitrones, when reacted with aromatic and aliphatic aldehydes in refluxing toluene or tetrahydrofuran, formed the corresponding aldonitrones (Z)- 10 , the latter arising from the fragmentation of an initially formed 1 , 4 , 2 -dioxazolidine 6 to adamantan-2-one and an oxaziridine intermediate 11 , which then rearranges to (Z)- 10 .     

Ligand-induced control of C-H versus aliphatic C-C migration reactions of Rh carbenoids

The reaction of lithiated trimethylsilyldiazomethane (LTMSD) with aldehydes and subsequent quenching with TMSCl furnished relatively stable alpha-silylated diazocompounds. Upon treatment of the alpha-silylated diazocompounds with Rh2(OAc)4 in refluxing toluene, alpha-silyl silyl enol ethers were formed from unbranched and branched aliphatic aldehydes through predominantly 1,2-migration of the C-H bond. In contrast, treatment of the alpha-silylated diazocompounds with Rh2(tfa)4 at room temperature gave alpha-silyl silyl enol ethers through exclusive and unusual 1,2-migration of the C-C bond. The origin of the selectivity observed from the two catalysts is discussed in relation to early and late transition states.     

Reactions of dialkyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioates,-heptane-1,7-dioates with zinc and aromatic aldehydes

Zinc enolates generated from dimethyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioate and zinc reacted with aromatic aldehydes giving methyl 2,2-dimethyl-3-oxo-3-(5-oxo-2-aryltetrahydrofuran-3-yl)propanoates. The reaction of zinc enolates obtained from dimethyl 4-bromo-2,2-dimethyl-3-oxoheptane-1,7-dioate and zinc with aromatic aldehydes depending on the synthesis conditions led to the formation either methyl 2,2-dimethyl-3-oxo-3-(6-oxo-2-aryltetrahydropyran-3-yl)propanoates or 3-(5,5-dimethyl-4,6-dioxo-2-aryltetrahydropyran-3-yl)propanoates. The compounds synthesized formed as a single diastereomer of E-configuration.     

The reaction of diethyl oxalate with some azolidones

The condensation of thiazolidine-2, 4-dione, rhodanine, isorhodanine, 2-thiohydantoin, and pseudothiohydantoin with diethyl oxalate has given products which are azolidone-5-glyoxalic acids or their esters. In these compounds, the glyoxalic acid residue is readily replaced under the action of diazonium salts, aromatic nitroso compounds, and aromatic aldehydes with the formation of 5-arylazo-, 5-arylimino-, and 5-arylideneazolidones. 5-Arylidenerhodanines are also formed from 5-isopropylidene-and 5-(β-acetyl-α-methylethylidene)rhodanines by their reaction with aromatic aldehydes and ketones.     

Reactions of [NH<Stack><Subscript>3</Subscript><Superscript>+·</Superscript></Stack>, H<Subscript>2</Subscript>O] with carbonyl compounds: A McLafferty rearrangement within a complex?

The reactions of the water solvated ammonia radical cation [NH(3)(+*), H(2)O] with a variety of aldehydes and ketones were investigated. The reactions observed differ from those of low energy aldehydes and ketones radical cations, although electron transfer from the keto compound to ionized ammonia is thermodynamically allowed within the terbody complexes initially formed. The main process yields an ammonia solvated enol with loss of water and an alkene. This process corresponds formally to a McLafferty fragmentation within a complex. With aldehydes, another reaction can take place, namely the transfer of the hydrogen from the CHO group to ammonia, leading to the proton bound dimer of ammonia and water, and to the NH(4)(+) cation. Comparison between the available experimental results leads to the conclusion that the McLafferty fragmentation occurs within the terbody complex initially formed, with no prior ligand exchange, the water molecule acting as a spectator partner.     

Reactions of 4-oxo-1,3-benzoxazinium perchlorates with guanidines

Condensation of 2-methyl-4-oxo-1,3-benzoxazinium perchlorate with various aromatic and heterocyclic aldehydes provided previously unknown arylvinyl-and hetarylvinyl-substituted salts whose recyclization under treatment with guanidine resulted in formerly undescribed 1,3,5-triazines. The reaction of perchlorates obtained with guanidinebenzoxazole led to the formation of bishetarylamines, with guanidinebenzimidazole formed triazinebenzimidazoles, the cyanoguanidine reacted with 4-oxo-1,3-benzoxazinium perchlorates to give cyanamides.     

Reactions of lithiated (E)-3-halo-1-phenylsulfonylprop-1-enes and (Z)-1-halo-3-phenylsulfonylprop-1-enes with aldehydes

(E)-3-Chloro-1-phenylsulfonylprop-1-ene and its iodo- and bromo-analogues, (Z)-1-iodo-3-phenylsulfonylprop-1-ene and (Z)-1-bromo-3-phenylsulfonylprop-1-ene, have each been successfully converted into lithiated carbanions which react regioselectively with aromatic aldehydes to give gamma-alkylated products whose nature depends upon the halogen substituent: the chloro-sulfones yield (2Z)-1-aryl-2-chloro-4-phenylsulfonylbut-2-en-1-ols but the bromo- and iodo-derivatives behave differently, yielding (1E)-trans-4-aryl-3,4-epoxy-1-phenylsulfonylbut-1-enes. In sharp contrast, the same lithiated sulfones react with aliphatic aldehydes to give anti-configured beta-hydroxysulfones which are formed via diastereoselective alpha-alkylation reactions.     

Synthesis of 2-Aryl and 2-Hetaryl Derivatives of 2'-Aminospiro[(1,3-dioxane)-5,5'-thiazolin]-4'-one and Spiro[(1,3-dioxane)-5,5'-thiazolidine]2',4'-dione

2-(Het)aryl derivatives of 2'-aminospiro[(1,3-dioxane)-5,5'-thiazolin]-4'-one or spiro[(1,3-dioxane)-5,5'-thiazolidine]-2',4'-dione are formed by the acid catalyzed interaction of 2-amino-5,5-bis(hydroxymethyl)-4-thiazolinone or its oxo analog 5,5-bis(hydroxymethyl)thiazolidine-2,4-dione with (hetero)aromatic aldehydes.     

Directions of reactions of 6-amino-, -acetylamino-, and -benzoylaminodeoxyvasicinones with aldehydes

6-Acetylamino- and -benzoylamino-9-arylidenedeoxyvasicinones were synthesized by reaction of 6-amino(3), -acetylamino- (4), and -benzoylamino- (5) -deoxyvasicinones (DOV) with aromatic aldehydes and furfurol in glacial acetic acid. It was shown that the amino group of 6-aminodeoxyvasicinone underwent acylation upon reaction with aldehydes to form 6-acetylamino-DOV, which reacted with aldehydes to form 9-arylidene derivatives. Carrying out this condensation in toluene, o-xylene, and ethanol produced a mixture of condensation products at the 6-amino-and a-CH₂-groups. It was found that condensati on of 3 with 4-nitrobenzaldehyde in pyridine formed exclusively the Schiff bases. Methods for preparing 6-nitrodeoxyvasicinone and for its reduction were improved.     

The heterodiene synthesis

The reaction of benzamidine with aromatic aldehydes gives 2-aryl-4, 6-diphenyl-1, 2-dihydro-sym-triazines. These compounds react as heterodienes with acetylenedicarboxylic ester. In this process, the triazine ring is cleaved with the splitting out of the imine of an aromatic aldehyde, and the ester of 2,4-diphenyl-5,6-pyrimidinedicarboxylic is formed.For part I, see [4].     

Isomerization of Aldehydes Catalyzed by Rhodium(I) Olefin Complexes

A mixture of isomeric aldehydes is formed in a catalytic isomerization of alkyl aldehydes with [C(5)Me(5)Rh(olefin)(2)] complexes. This process offers an indirect method for altering the n:iso ratio of aldehydes formed in hydroformylation reactions. For example the reaction of n-butanal with [C(5)Me(5)Rh(CH(2)=CHMe)(2)] (1) results in the formation of a bis-alkyl carbonyl rhodium complex 2 which is the resting state during the isomerization of n-butanal to a mixture of n- and iso-butanals (see scheme). In the presence of other olefins transfer formylation is observed.     

Room temperature-stable electride as a synthetic organic reagent: application to pinacol coupling reaction in aqueous media

Room temperature-stable inorganic electride [Ca(24)Al(28)O(68)](4+)4e(-) was employed for a pinacol coupling reaction in aqueous media. Ca-Al-O gel formed by the destruction of the crystal structure of an electride by water media played a key role in transferring the electron to electrophilic aldehydes. Aromatic aldehydes reacted smoothly with moderate to high yields.     

Intramolecular and Intermolecular Schmidt Reactions of Alkyl Azides with Aldehydes

Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes were studied in both intermolecular and intramolecular contexts. The intramolecular reactions of azidoalkyl aldehydes in which the azide and carbonyl groups were separated by 2-5 carbons were examined. Although the examples having the shortest tether failed (3-azidopropanals), each of the other systems gave good yields of either NH-substituted lactams (resulting from hydride migration in the initially formed azidohydrin adduct) or formamides (alkyl migration). The product formed was dependent on the chain length of the starting azido aldehyde. The intermolecular reactions were less efficient, requiring TiCl₄ promotion for even moderate yields, and in each case gave mixtures of products resulting from hydride and alkyl migration.     

The chain lengthening of aliphatic aldehydes with the aid of “nucleophilic carbene”

The addition of “nucleophilic carbene” on 1,2,4-triazole bases ($\text{2}$) and aldehydes is decisively influenced by the anion present. 5-(α-Hydroxyalkyl)-1,2,4-triazolium chlorides, formed in the addition reaction of 3-methylthio-1,4-diphenyl-1,2,4-triazolium chloride ($\text{1c}$) with aldehydes, can be easily reduced to 5-alkyl-1,2,4-triazolium iodides ($\text{5}$). Reduction of these with NaBH₄ affords aldehydes by acidic hydrolysis or carboxylic acids by alkaline hydrolysis, the carbon chain of which has been lengthened by one CH₂ group, as compared to the starting aldehyde.     

Synthesis of 2-(4-Hydroxy-6-methyl-2-oxo-2H-pyran-3-carbonyl)-6,6-dimethyl-3-phenyl-3,5,6,7-tetrahydro-2H-benzofuran-4-one Derivatives via Multicomponent Reaction

A sequential one-pot, two-step reaction for an efficient preparation of 2-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-carbonyl)-6,6-dimethyl-3-phenyl-3,5,6,7-tetrahydro-2H-benzofuran-4-one derivatives has been described. One-pot reaction of in situ–formed benzopyran-substituted pyridinium ylides with aromatic aldehydes and dimedone gives corresponding 2,3-dihydrofurans in good yields. The structures of all the newly synthesized compounds were confirmed from their analytical and spectral data.     

Photochemische Cycloadditionen von 3-phenyl-2h-azirinen mit Aldehyden. 31. Mitteilung über Photoreaktionen

Experiments concerning the photochemical condensation of 3-phenyl-2H-azirines 1 with aliphatic and aromatic aldehydes to 3-oxazolines 4 are fully described (cf. scheme 1 ). Photochemically nitrile methylides of type 2 are first formed, which then very quickly react thermally with the aldehydes in a regiospecific manner to give the 3-oxazolines 4 . Azirines monosubstituted in position 2 (l b and 1 c ) give mixtures of cis, trans-oxazoline isomers, in which the cis isomer predominates. The stereoselectivity of the cycloaddition reaction can be rationalized by a simple model (scheme 10). The stereoisomeric 3-oxazolines 4 are distinguishable in the NMR. spectra by the large homoallylic coupling constants between the H atoms on C(2) and C(5).     

The putative Diels-Alderase macrophomate synthase is an efficient aldolase

We find that the putative Diels-Alderase macrophomate synthase (MPS) catalyzes the addition of pyruvate enolate, generated by decarboxylation of oxaloacetate, to a variety of aldehydes. Alkyl, aryl, and heteroaryl aldehydes are accepted as substrates, providing gamma-hydroxy-alpha-ketoacids in 35-95% yield with modest levels of stereochemical control. These aldol products, which are difficult to synthesize by other methods, are formed with efficiency comparable to that of macrophomate. Our results thus provide evidence that a two-step Michael-aldol pathway is a plausible alternative to the postulated [4 + 2] cycloaddition in the MPS-catalyzed addition of pyruvate enolate to 2-pyrones. They are also relevant to understanding the divergent evolution of type II pyruvate aldolases.