Aldehyde 1-acylation

A1BN, iw azobisisnbutyronilrile aldehydes, acyl radicals from 1 18 alkanelhiyl radicals Irom ally] sulfides 300 from disunities 291-2 from thiols 290, 291 polarity 290... 

Sulphated zirconia catalysts can be acidic or superacidic depending on the method of treatment. A variety of acid-catalysed reactions, referred to earlier in this section, can be carried out with sulphated zirconia. Yadav and Nair (1999) have given a state-of-the art review on this subject. Examples of benzylation of benzene with benzyl chloride / benzyl alcohol, alkylation of o-xylene with. styrene, alkylation of diphenyl oxide with 1-dodecene, isomerization of epoxides to aldehydes, acylation of benzene / chlorobenzene with p-chloro benzoylchloride, etc. are covered in the review. 

Reactive structures that interfere with the biochemical assay (aldehydes, acyl-halides, sulfonyl-halides, Michael acceptors, epoxides, aziridines, oximes, N-oxides). 

The benzoin reaction typically consists of the homocoupling of two aldehydes, which results in the formation of inherently dimeric compounds, therefore limiting the synthetic utility. The aoss-benzoin reaction has the potential to produce four products, two homocoupled adducts and two cross-benzoin products. Several strategies have been employed to develop a selective cross-benzoin reaction, including the use of donor-acceptor aldehydes, acyl silanes, acyl imines, as well as intramolecular reactions. 

The dithian 33 was made from the available aldehyde, acylated with CO2 to give 34 and the dithian hydrolysed with Cu(II) catalysis to give the a-ketoacid 30 all in excellent yield. Dithians are easy to make, stable and easy to use, but the deprotection can be tricky. 

A kinetic isotope effect was observed327 only for a-D-substituted aldehydes. Acyl radicals, thus, are formed only as a result of the secondary reactions,... 

The insertion of CO into M—C bonds to give acyls is reversible (Section 21-5). However, CO can be irreversibly removed from organic molecules these reactions involve acyl intermediates. Thus aldehydes, acyl, and aroyl halides can be decarbo-nylated either stoichiometrically or catalytically by complexes such as RhCl(PPh3)3 or RhCl(CO)(PPh3)2. An example of a stoichiometric decarbonylation is... 

Organozinc addition reactions to unsaturated systems lead to an intermediate zinc compound which is in most cases further hydrolyzed to give the corresponding protonated organic compound. This intermediate can also be trapped by reaction with electrophiles (see Electrophile) (E+) such as aldehydes, acyl chlorides, organic halides, silyl halides, and so on. Depending on the nature of the electrophile (see... 

The rhodium complex [RhCl(PPh3)3] readily brings about stoichiometric decarbonylation of aldehydes, acyl halides and diketones. A typical aldehyde decarbonylation is illustrated by equation (69). a,3-Unsaturated aldehydes are decarbonylated stereospecifically (equation 70), while with chiral aldehydes the stereochemistry is largely retained (equation 71). ° ... 

Aldehyde acylals substitute one of the acetoxy groups by the trichloromethyl anion, generated under phase-transfer catalytic conditions. Acylals of a, -unsaturated aldehydes may also add dichlorocarbene however, substitution by the trichloromethyl anion precedes cyclo-propanation (Houben-Weyl, Vol. E19b, pp 1587-1588), e.g. formation of 3. ... 

Monoacylation of 2,3-diaminoquinoxalines has been achieved by reaction with an acid anhydride in THF. Under more vigorous conditions reaction of 2,3-diaminoquinoxalines with acid anhydrides results in ring closure to an imidazo[ ]quinoxaline. Similar ring closures have been carried out with aldehydes, acyl halides, formic acid, orthoesters, and urea. Polycyclic compounds have also been prepared from 2,3-diaminoquinoxaline by reaction with 1,-2-dicarbonyl compounds and 1,2-diamines, as illustrated in Scheme 7. 

Structure of a,[3-unsaturated compound unreactive C=0 group (amide, ester) reactive C=0 group (aldehyde, acyl chloride)... 

The decarbonylation of aldehydes, acyl halides, aroyl halides, alcohols, or ketones is a useful and important reaction in organic synthesis/ Although several methods not utilizing transition metals are known " (including various deformylation reactions and thermal and photochemical decarbonylatlons), they are not general and not usually applicable under mild conditions where undesirable side reactions are minimized/ ... 

Toxicology Toxic harmful or fatal if swallowed may cause eye/skin irritation, nausea, abdominal pain, vomiting, headache, dizziness, weakness, confusion, drunken behavior, visual disturbances, drowsiness, coma liver/kidney/heart damage in massive doses Precaution Flamm. liq. incompat. with alkali metals, acids, aldehydes, acyl chlorides... 

Sonosynthesis of cyanohydrin esters from aldehydes, acylating agent, and solid potassium cyanide in acetonitrile is a useful method as a substitute for liquid-liquid phase transfer catalyzed reactions. This method is applicable for the preparation of pyrethroid insecticides such as Cyphenothrin or Fenvalerate . 

Reaction with Carbon Electrophiles. The ability of this reagent to transfer the benzothiazol-2-yl unit to carbon electrophiles, is demonstrated by reactions with aldehydes, acyl hahdes, and chloroformates that give trimethylsilyl carbinols, ketones, and esters (eq 1). ... 

Some rhodium compounds, especially (Ph3P)3RhCl, catalyze the elimination of CO from aldehydes, acyl halides, and acyl cyanides, probably by CO elimination from acylrhodium compounds (J45). 

Pd is an efficient catalyst for carbonylation of olefinic and acetylenic compounds and aryl halides to form various saturated and unsaturated carboxylic acids, their esters, and lactones. Also, aldehydes are obtained using Pd catalysts. For a long time, Pd has been known as an efficient catalyst for decarbonylation of aldehydes. Acyl halides are also de-carbonylated with Pd catalysts. Now it is well-established that Pd is the efficient catalyst for both carbonylation and decarbonylation as reversible processes. 

The educts 72/77 are synthesized (a) from aUyl alcohols 71 by addition to methoxyallene and (b) from ethyl vinyl ether by metalation, addition of an aldehyde, acylation, and Takai olefination ( 75 —> 76). 

Aldehydes, acyl chlorides, esters, and carboxylic acids are reduced by hydride ion to primary alcohols ketones are reduced to secondary alcohols and amides are reduced to amines. 

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