Azo Diels—Alder reaction

Kresze et al. have described an interesting pyrrole synthesis based on an azo Diels-Alder reaction [Eq. (16)].43... 

The azo Diels-Alder reaction is another example of a [4-f2] cycloaddition with a dienophile that contains two heteroatoms. Therefore, two C—N bonds are created during this process where 3,4-dehydro-1,2-piperazines 200 are synthesized from azo dienophile 198 (Scheme 41.42). ... 

Unfortunately, this reaction has not yet reached its fid potential for the stereoselective total synthesis of natural products. It is easy to recognize that piperazic acid derivatives 201 could develop from an azo Diels-Alder reaction. These nonproteinogenic cyclic a-hydrazino acids are widely found in depsipeptide natural products like the antimycobacteria lydiamycins 202 isolated from the fermentation broth of Streptomyces lycidus or in cdazapril 203 an angiotensin-converting enzyme inhibitor used as an antihypertensive drug by Hoffman-Laroche (Scheme 41.43). ... 

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See also in sourсe #XX -- [ , ]

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