Arenes aldehydes

Producing aldehyde groups (CHO) from alkenes is known as hydroformulation — an aldehyde and a hydrogen atom are added to a carbon-carbon double bond. Usually, the aldehydes aren t the final desired product instead, the aldehydes are commonly treated with hydrogen to produce primary alcohols (RCH2OH). Historically, hydroformylation is a key reaction to the development of the modern field of industrial chemistry. 

Many aldehydes and ketones are made m the laboratory from alkenes alkynes arenes and alcohols by reactions that you already know about and are summarized m Table 17 1... 

The condensation of an aldehyde with resorcinol gives rise to calix (3) arene (114). Isoprene reacts with resorcinol under acidic conditions to give ben2odipyran (24) and monochroman (25) (115). 

The first use of chiral oxazolines as activating groups for nucleophilic additions to arenes was described by Meyers in 1984. " Reaction of naphthyloxazoline 3 with phenyllithium followed by alkylation of the resulting anion with iodomethane afforded dihydronaphthalene 10 in 99% yield as an 83 17 mixture of separable diastereomers. Reductive cleavage of 10 by sequential treatment with methyl fluorosulfonate, NaBKi, and aqueous oxalic acid afforded the corresponding enantiopure aldehyde 11 in 88% yield. 

Abstract The photoinduced reactions of metal carbene complexes, particularly Group 6 Fischer carbenes, are comprehensively presented in this chapter with a complete listing of published examples. A majority of these processes involve CO insertion to produce species that have ketene-like reactivity. Cyclo addition reactions presented include reaction with imines to form /1-lactams, with alkenes to form cyclobutanones, with aldehydes to form /1-lactones, and with azoarenes to form diazetidinones. Photoinduced benzannulation processes are included. Reactions involving nucleophilic attack to form esters, amino acids, peptides, allenes, acylated arenes, and aza-Cope rearrangement products are detailed. A number of photoinduced reactions of carbenes do not involve CO insertion. These include reactions with sulfur ylides and sulfilimines, cyclopropanation, 1,3-dipolar cycloadditions, and acyl migrations. 

The reductive transformation of arene carboxylates to the corresponding aldehydes under aerobic conditions has already been noted. In addition, aromatic aldehydes may undergo both reductive and oxidative reactions, with the possibility of decarboxylation of the carboxylic acid formed ... 

Table 1.2 Examples of double and triple bond hydrogenation with recyclable metal NPs in ILs alkenes, dienes, arenes, ketones, and aldehydes. 

Arenes, polyalkyl, oxidation with per-oxytrifluoroacetic acid and boron trifluoride, 48, 89, 90 Arenesulfonyl chlorides, reaction with 3-amino-3-pyrazoline, 48, 11 Aromatic aldehydes. Mesitalde-HYDE, 47, 1... 

Oxidation of silyl enol ethers. Oxidation of silyl enol ethers to a-hydroxy aldehydes or ketones is usually effected with w-chloroperbenzoic acid (6, 112). This oxidation can also be effected by epoxidation with 2-(phenylsulfonyl)-3-( p-nitrophenyl) oxaziridine in CHC1, at 25-60° followed by rearrangement to a-silyloxy carbonyl compounds, which are hydrolyzed to the a-hydroxy carbonyl compound (BujNF or H,0 + ). Yields are moderate to high. Oxidation with a chiral 2-arene-sulfonyloxaziridine shows only modest enantioselectivity. 

We have found several examples in which adjacent cationic charge centers are shown to activate carboxonium electrophiles. A convenient method for studying this activation is through the use of the hydroxyalkylation reaction, a commercially important, acid-catalyzed condensation of aldehydes and ketones with arenes.10 It is used for example in the synthesis of bis-phenol A from acetone and phenol (eq 6). While protonated acetone is able to react with activated arenes like phenol, it is not capable of reacting with less nucleophilic... 

Among the many useful electrophiles, carbonyl compounds and their derivatives lead to products of the highest value for synthetic endeavors. First experiments with aldehydes and ketones were performed by Hoff, Brandsma and Arens (Scheme 8.15) [12b]. The primary allenyl adducts 60, which are isolable in moderate to excellent yields [12b, 47], serve as starting materials for subsequent cyclizations (see Section 8.2.2.2). 

The reaction of (dibromomethyl)arenes with sodium acetate and calcium carbonate under liquid liquid conditions yields not the bisacetoxy derivative but the aldehyde in high yield (65-82%) [29,30]. 

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