Diazo aldehydes

The reaction has also been applied to compounds with other leaving groups. Diazo ketones, diazo esters, diazo nitriles, and diazo aldehydes react with trialkylboranes in a similar manner, for example. 

The mechanism is probably also similar. In this case, a base is not needed since the carbon already has an available pair of electrons. The reaction with diazo aldehydes is especially notable, since successful reactions cannot be obtained with a-halo aldehydes. ... 

Alkylation and hydrolysis of imines alkylation of aldehydes 10-107 Alkylation and hydrolysis of dithianes 10-108 Alkylation and hydrolysis of oxazines and similar compounds 10-109 Reaction of diazo aldehydes with boranes... 

Diazocycloalkanones with five- to twelve-membered rings can be synthesized by the present procedure in good yields (Table I).4 Diazo transfer with deformylation can also be used for the preparation of bicyclic a-diazo ketones.10,11 A related procedure involving reaction of the sodium salt of an a-(hydroxy methylene)-ketone with p-toluenesulfonyl azide in ethanol has been applied to the synthesis of diazoalkyl ketones, a-diazo aldehydes, and a-diazo carboxylic esters.12... 

Allyldiethylamine behaves similarly, but the yields are low since neither the starting amine nor the products are stable to the reaction conditions. For the efficiency of the cyclopropanation of the allylic systems under discussion, a comparison can be made between the triplet-sensitized photochemical reaction and the process carried out in the presence of copper or rhodium catalysts whereas with allyl halides and allyl ethers, the transition metal catalyzed reaction often produces higher yields (especially if tetraacetatodirhodium is used), the photochemical variant is the method of choice for allyl sulfides. The catalysts react with allyl sulfides (and with allyl selenides and allylamines, for that matter) exclusively via the ylide pathway (see Section 1.2.1.2.4.2.6.3.3. and Houben-Weyl, Vol. E19b, pll30). It should also be noted that the purely thermal decomposition of dimethyl diazomalonate in allyl sulfides produces no cyclopropane, but only the ylide-derived product in high yield.Very few cyclopropanes have been synthesized by photolysis of other diazocarbonyl compounds than a-diazo esters and a-diazo ketones, although this should not be impossible in several cases (e.g. a-diazo aldehydes, a-diazocarboxamides). Irradiation of a-diazo-a-(4-nitrophenyl)acetic acid in a mixture of 2-methylbut-2-ene and methanol gave mainly l-(4-nitrophenyl)-2,2,3-trimethylcyclo-propane-1-carboxylic acid (19, 71%) in addition to some O-H insertion product (10%). ... 

Transfer of a formylcarbene unit from an a-diazo aldehyde to an alkene has never become popular. The copper-catalyzed cyclopropanation with diazoacetaldehyde to give 5 occurred in low yield, since ketene formation is competitive (for experimental procedure, see Houben-Weyl Vol.E19b, pi224). It appears that with other catalysts and at a lower temperature the cyclopropanation could be more effective. 

The reaction of chlorodimethylformiminium chloride (XXII) with diazoketones and ethyl diazoacetate gives rise to the formation of a-diazo-aldehydes XXIII ( ). In contrast, diazomethane undergoes reaction with XXII to yield 2-dimethylamino-l,3-dichloropropane ( ). 

Ring enlargement of benzene derivatives by carbenes generated from diazo compounds (better in the presence of a Rh catalyst) Conversion of aldehydes to ketones by diazo compounds (Schlotterbeck) see also Ptau Planer... 

On treatment with alkaline reagents, -toluenesulfonylhydra-zones of aldehydes and ketones yield diazo compounds which decompose in hydroxylic solvents to yield olefinic (or bicylic) compounds and in aprotic solvents to yield olefins and cyclo-propanes. ... 

The cyclic diazo compounds (diazirines 65) are very unreactive compounds. Specially noticeable is the absence of the reactivity toward electrophilic reagents which is characteristic of the linear isomers. Acids or aldehydes which react smoothly with the aliphatic diazo compounds are without action on the cyclic diazo compounds. Iodine does not attack the cyclic diazo compounds. 

The sulfur ylide-mediated epoxidation of aldehydes has been thoroughly investigated [70, 71]. The chiral sulfur ylides reported by Aggarwal have been most broadly applicable, and a catalytic, asymmetric process yielding aromatic transepoxides has been developed [72]. In this process, the sulfur ylides are produced in situ from diazo compounds, generated in turn from tosylhydrazone salts (Scheme 9.15) [73],... 

Nearly all (extranuclear) hydrazonoquinoxalines are made by treatment of quinoxaline aldehydes, ketones, or their acetals with hydrazine or substituted hydrazine, but a few are produced by diazo coupling. These reactions are illustrated by the following examples. 

Enzymes (glutaric aldehyde-linked) Dopamine (Diazo-coupled)... 

In contrast to aldehydes, simple ketones are poor substrates for Fe-catalyzed olefinations due to their weak electrophilicity. Decreasing the electron density of carbonyl group can facilitate olefination of ketones with diazo compounds. 

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