Stereoselective synthesis of spirocyclic derivatives of functionalized 2,3,4,7-tetrahydro-1 H-azepines

A simple and effective stereoselective synthesis of unique azaspirocyclic 2,3,4,7-tetrahydro-1 H -azepine derivatives, namely, 7-azaspiro[4.6]undec-9-ene and 8-azaspiro[5.6]dodec-10-ene, from simple commercially available reagents was accomplished. Their key 1,2 -epoxy derivatives as individual diastereomers were obtained in nine steps with 31-32% overall yields. The possibility of synthesizing a library of small spiroheterocyclic molecules was exemplified by the N -Boc-protected (1 RS ,2 SR ,6 RS )-1,2-epoxy-8-aza- spiro[5.6]dodec-10-ene scaffold through simple chemical modifications of its epoxide function.