Aldehydes reactions with diazoalkanes

Condensation with carbonyl compounds. Formation of epoxides from aldehydes by reaction with sulfonium ylides is subject to asymmetric induction. The latter species have been generated from 91, 92, and 93, and also those derived from monoterpenes, e.g., 94 " and 95.- Of course the ylides can be obtained in situ by deprotonation of sulfonium salts or copper-catalyzed decomposition of diazoalkanes (with the carbenoids trapped by the sulfides). 

Three-membered heterocycles. Decomposition of diazo compounds by the iron complex in the presence of imines leads to aziridines. An analogous reaction of diazoalkanes with aldehydes gives some epoxides and the rearrangement products (ketones) owing to the Lewis acidic nature of the catalyst. Ethyl diazoacetate behaves differently, as 1,2-aryl shift occurs during the reaction. ... 

Syntheses and properties of acetylenic derivatives of pyrazoles 02AHC(82)1. Syntheses of 2-pyrazolines by the reactions of a,/ -unsaturated aldehydes, ketones, and esters with diazoalkanes, nitrile imines, and hydrazines 02JHC1. 

Homologation of carbonyl compounds. The very bulky organoaluminums promote reaction of aldehydes and ketones with diazoalkanes. Aldehydes afford ketones. 

A proposed reaction pathway by which ammonia is formed is shown in Scheme 6. After the dissociation of phosphine, attack by another hydrazido complex (e.g., A) to form a bridged species, C, is proposed. Hydrazido complexes such as A are known to be good nucleophiles. For example, they react in acid catalyzed reactions with aldehydes and ketones to form diazoalkane complexes (e.g.. Equations 4 and... 

This reaction has been extended to directly convert aldehydes into -keto esters by reacting with ethyl diazoacetate in the presence of a catalytic amount of SnCl2. In addition, the reaction between diazoalkanes and acyl halides to form a-halomethyl ketones, known as the Nierenstein Reaction, should be considered as another extension of the Schlotterbeck reaction. 

The reaction of diazoalkanes with carbonyl-containing compounds dates back to observations made by Buchner and Curtius as early as 1885 [56]. Although others examined this novel reactivity pattern [57,58], Schlotterbeck is largely credited with uncovering the merger of aldehydes and diazoalkanes in 1907 [59, 60]. Schlotterbeck was able to confirm by careful experimentation that various aliphatic aldehydes afforded the corresponding methyl ketones when treated with diazomethane. The reaction of aldehydes with diazomethane to form methyl ketones (Scheme 3) later became known as the Buchner-Curtius—Schlotterbeck reaction [61]. Application of this chain elongation to ketmies and eventually cycloalkanones did not come until several decades later and required a critical new discovery. 

Sulphone syntheses based upon sulphinic acids include addition to activated alkenes, " condensation of salts RSOz Na" with Mannich bases or with an aldehyde and a urea or a thiourea in a Mannich-type reaction, and reaction with a diazoalkane benzhydryl p-tolyl sulphone is formed... 

Aldehydes and ketones can also be converted to epoxides by treatment with a diazoalkane,most commonly diazomethane, but an important side reaction is the formation of an aldehyde or ketone with one more carbon than the starting compound (Reaction 18-9). The reaction can be carried out with many aldehydes, ketones, and quinones. A mechanism that accounts for both products is... 

The reaction of diazomethane derivatives with aldehydes and ketones, though a fairly well-studied field now, continues to be a source of practical extensiori/homologation technologyThe general reaction is outlined in Scheme 4. The diazoalkane, shown in resonance forms (11a) and (11b), reacts with... 

Aldehyde oleflnation.4 CH3Rc03 (1) js an efficient catalyst for condensation of aldehydes with a diazoalkane and a phosphine to form an alkenc and a phosphine oxide. The actual catalyst may be CH.iRe020PR,. The reaction is applicable to aliphatic and aromatic aldehydes and also to cnals. Some cyclokctones undergo this oleflnation but in only moderate yield. 

Bamford-Stevens and Shapiro Reactions. The Bamford-Stevens reaction is used to obtain unsaturated compounds from tosylhydrazones. A base is required to generate its monoanion, which thermally decomposes to yield the corresponding di-azo derivatives. These reactive species evolve to give an aUcene through carbenium ions in protic solvents or carbenes in aprotic solvents. The thermal decomposition of the monoanions of trisyl-hydrazones is commonly used to obtain diazoalkanes for different applications such as functionalization of solid supports, epox-idation and alkenylation of aldehydes, or the study of radicals and carbenes The functionalization of a Merrifield resin with... 

---