Aldehydes Addition products

The elaboration of the polyunsaturated side chain of asteltoxin requires a stereoselective coupling of aldehyde 2 with a suitable synthetic equivalent for the anion of 4-formyl-1,3-butadiene (see intermediate 3 in Scheme 4). Acid-induced skeletal reorganization of the aldehyde addition product, followed by an intermolecular... 

In 1998, Miyaura reported a Rh(acac)(CO)2/dppp-catalyzed addition of aryl or alkenylboronic acids to aldehydes in aqueous organic mixtures under an inert atmosphere (Eq. 8.85).216 The use of electron-rich tri(tm-butyl)phosphine as ligand was found to be beneficial for obtaining good yields of the corresponding aldehyde addition products.217... 

This system also worked well in ionic liquids.518 Li etal. found silver-phosphine complexes to promote aldehyde-alkyne coupling in water. When triphenylphosphinesilver chloride was used as a catalyst in water, the only detected product was the aldehyde addition product instead of the adduct derived from imine (Scheme 111).519... 

Dihydro derivatives are readily formed in reactions with aldehydes and ketones, and aldehyde addition products can be dehydrogenated to the fully conjugated heterocycles <1981RCR816, 1995AQ151>. In a new procedure, palladium iodide-catalyzed carbonylation of 1,8-naphthalenediamine 918 gave 2(l//)-perimidinone 921 in 91% yield <2004JOC4741>. 

AUyl bromide reacted with tin in the presence of a mixture of benzaldehyde and acetophenone in a 5 1 H2O/THF solvent mixture to give 90% yield of the aldehyde addition product whereas the ketone did not react at all under these competitive conditions [92] ... 

The ( -y-(silyl) allyl boronates 47 and 48 were subsequently introduced in order to access more highly oxygenated aldehyde addition products. For example, the allylic silane addition products can undergo subsequent oxidation to provide 1,2- and 1,4-diol products. The allylsilane products are also allylmetal reagents Roush and co-workers have demonstrated their ability to undergo addition reactions with Lewis acid activated aldehydes to form tetrahydrofuran products. ... 

Lavis and Ellman reported an efficient method for the preparation of Af-aryl-2//-indazoles 18 by Rh(III)-catalyzed C-H bond addition of azobenzenes to aldehydes without external oxidant (Eq. (5.18)) [13]. In this reaction, the regioselective activation of azobenzenes can be controlled either by electronic or by steric effects, and the azo moiety serves as a nucleophile to trap the initial aldehyde addition product. A wide range of aldehydes and azobenzenes participate in the reaction to afford differently substituted indazoles. An interesting feature of this reaction... 

Aldehydes form addition products at the double bond of the carbonyl (>C 0) group, and hydrolysis gives secondary alcohols. Thus acetaldehyde gives isopropyl alcohol ... 

Note, (a) Aqueous solutions of formaldehyde and acetaldehyde give these addition products, which are so soluble that they rarely separate this reaction is therefore an unsatisfactory test for these aldehydes. (6) These addition products are also formed by ketones (p. 345). 

The aniline then reacts with the ap-unsaturated aldehyde by 1 4-addition the addition product, under the influence of strong acid, cyclises to form 1 2-dihydroquinaldine. The latter is dehydrogenated by the condensation products of aniline with acetaldehyde and with crotonaldehyde simultaneously produced ( .c., ethylideneaniline and crotonylideneaniline) these anils act as hydrogen acceptors and are thereby converted into ethylaniline and n-butyl-aniline respectively. 

Not-Strike may have seen. But what Dr. Quack did that SWINS did not was use the bisulfite test with positive results. What does that mean It means that some doublebonded oxygen was formed, unless Dr. Quack was fibbing to us, It cannot have been a propiophenone (don t ask) because propiophenones cannot form the bisulfite addition product. Could an aldehyde have formed (don t ask) Maybe. But highly unlikely considering the mechanism of the reaction. 

The 2-metalated thiazoles react with a variety of electrophilic substrates in a standard way, leading to addition products with aldehydes, ketones, carbon dioxide, epoxides, nitriles, Schiff bases, and to substitution products with alkyl iodides (12, 13, 437, 440). 

Conjugation of the newly formed double bond with the carbonyl group stabilizes the a p unsaturated aldehyde provides the driving force for the dehydration and controls Its regioselectivity Dehydration can be effected by heating the aldol with acid or base Normally if the a p unsaturated aldehyde is the desired product all that is done is to carry out the base catalyzed aldol addition reaction at elevated temperature Under these conditions once the aldol addition product is formed it rapidly loses water to form the a p unsaturated aldehyde... 

As with other reversible nucleophilic addition reactions the equilibria for aldol additions are less favorable for ketones than for aldehydes For example only 2% of the aldol addition product of acetone is present at equilibrium... 

Aldehydes form addition products with sulfamic acid salts. These are stable ia neutral or slightly alkaline solutions but are hydroly2ed ia acid and strongly alkaline solutions. With formaldehyde, the calcium salt of the methylol (hydroxymethyl) derivative [82770-57-8], Ca(02SNHCH20H)2, is obtained as a crystalline soHd. 

Solutions of RC triple-bond C—Ti(0-/-C2H2)2 can be prepared by treating acetylenic compounds, such as phenylacetylene, with butyl lithium and then Cl—Ti(0-/-C2H2)2. These materials can react with aldehydes and epoxides to give the expected addition products (215). 

Chloral forms well-crystallized adducts (126) with diaziridines containing at least one NH group (B-67MI50800). Carbonyl addition products to formaldehyde or cyclohexanone were also described. Mixtures of aldehydes and ammonia react with unsubstituted diaziridines with formation of a triazolidine ring (128). Fused diaziridines like (128) are always obtained in ring synthesis of diaziridines (127) from aldehyde, ammonia and chloramine. The existence of three stereoisomers of compounds (128) was demonstrated (76JOC3221). Diaziridines form Mannich bases with morpholine and formaldehyde (64JMC626), e.g. (129). 

The material is triturated with saturated sodium bisulfite solution (2 cc. per gram), and after about three hours the pasty mixture is filtered with suction. The addition product is washed with absolute alcohol and then with ether and transferred to a flask fitted for steam distillation. Excess sodium carbonate solution is added and the aldehyde is distilled in a current of steam. 

An alternate method of producing the 21-hydroxy-20-ketone consists in lithium aluminum hydride reduction of the dimethyl acetal, hydrolysis to the 20-hydroxy-21-aldehyde and rearrangement, preferably via the bisulfite addition product... 

When acetic anhydride is used in the CF3CCI3 and zinc reaction with aldehydes, the initial addition product undergoes an elimination reaction to give 2-chloro-l,l,l-trifluoro-2-alkenes exclusively [60, 63] (equation 51)... 

The isolation of several pairs of geometric isomers of 4-unsaturated-5-oxazolones has been described. Generally, only one isomer is obtained when an aldehyde reacts with hippuric acid in the presence of acetic anhydride. Occasionally, mixtures have been separated in base-catalyzed reactions. In acetic anhydride-sulfuric acid or in 100% sulfuric acid, a mixture is obtained, and it has been suggested that sulfuric acid inhibits mutarotation of the intermediate addition product 53, which is a mixture of diastereomers (see, e.g., compound... 

Addition to unsaturated aldehydes results eitier in tlie 1,2 - or in tie 1,4-addition product, depending on tlie reaction conditions. Tluis, in tlie case of ciimam-aldebyde, tlie 1,2-additioii product is produced iii tlie presence of BF -OEtz and tie 1,4-addition product is obtained in tie presence of Me- SiCl (Scienie 2.46) [97]. 

---