Reactions of diazo ketones

When treated with boron trifluoride in ether, 3-diazo-l,l,l-triphenylacetone cyclizes almost quantitatively to l,l-diphenyl-2-indanone with loss of nitro-gen 786 

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Reaction of diazo ketones with hydrohalic acids... 

The Wolff rearrangement is well known as a reaction of diazo ketones, i.e. of diazoalkanes with a carbonyl group in a-position. Reaction 34 demonstrates that diazotized aminonaphthols are mesomeric with naphthoquinone diazides (48b) and that they have therefore also the character of quinonoid diazo ketones (see also Section II.C of this chapter). Wolff rearrangements take place also thermally and catalyzed by silver ions. 

Peptidyl bromomethyl ketones (Scheme 2) are synthesized by the same method used to prepare chloromethyl ketones (Scheme 1) namely, the reaction of peptidyl diazomethyl ketones with HBr. 16-18 This reaction proceeds readily for either chloromethyl or bromomethyl ketones, although a contaminant, the N-methylated compound, is usually observed in the final reaction product. 1 A variation of this method involves the use of LiBr, which facilitates the formation of acid-sensitive protected amino acids. 1 As with the chloromethyl synthesis, only Z and Boc should be used to protect the amino acids. 3 Although the reaction of diazo ketones with HBr is well known and relatively simple, only a few compounds have been synthesized (Table 2). 

Rhodium-catalyzed intramolecular reaction of diazo ketones like 175 leads mainly to carbenoid insertion into the a-C-H bond but a minor product is the 1,3-dioxolane (Equation 49) <1997JOC4910>. 

Diazo ketones also possess an electrophilic diazo group, and hence are susceptible to diazo-coupling reactions with suitable soft nucleophiles. Examples are given in equations (11) and (12). Phospha-zines such as (19) are useful synthetic intermediates in their own right. The carbon terminus of the 1,3-dipole possesses nucleophilic properties and can participate in aldol-type reactions with the particularly electrophilic carbonyl groups in 1,2-di- and 1,2,3-tri-carbonyl compounds. Intramolecular condensations occur with greater ease (equation 13). Reaction of diazo ketones of the type summarized in equations (9)-(12) have been thoroughly reviewed. ... 

Adducts (e.g., 5) from Tandem Cyclization-Cycloaddition Reaction of Diazo Ketone 4 with Dipolarophilcs General Procedure85 ... 

The catalyst (212) has also been successfully used as a cocatalyst in a highly diastereo- and enantioselective reaction of diazo ketones (213) with anilines (214) and ethyl glyojgrlate (215) providing chiral a,p-diamino acid derivatives (216) (Scheme 57)7 ... 

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