265669-18-9Relevant academic research and scientific papers
Asymmetric α-substitution versus aza Diels-Alder reaction of electron deficient N-sulfonyl imines
Morgan, Paul E.,McCague, Ray,Whiting, Andrew
, p. 515 - 525 (2007/10/03)
Several N-arylsulfonylglycine esters have been brominated under photolytic conditions to provide the corresponding α-bromoglycine. These bromo esters can be treated with a range of bases to generate N-sulfonyl imino esters in situ; attempts to isolate the imines in a pure state were universally unsuccessful. Once generated, the imines can be trapped with cyclopcntadiene to provide the corresponding aza Diels-Alder adducts in varying yields, depending upon the base used. In addition, if organometallic bases were employed (alkyllithiums and alkylaluminium reagents), not only were aza Diels-Alder adducts formed, but addition to the imine was also observed. In the case of organoaluminium reagents, imine addition was the major product. This process could be transformed into a stoichiometric asymmetric version, by generating a chiral aluminium reagent in situ to form a trialkyl (or trialkoxy) aluminium reagent, which when reacted with an N-sulfonyl bromoglycinate resulted in 19 to 62% enantiomeric excess of the corresponding substituted glycinate product. The Royal Society of Chemistry 2000.
