Transannular sulfur-nitrogen interaction in 1,5-thiazocine derivatives: an X-ray study

摘要: Abstract A sulfoxide-lactam ( 2 ) and sulfide- N -acetyllactam 3 ), each with a nine-membered, boat-like 1,5-thiazonine ring, have been prepared their molecular structures determined by X-ray diffraction. Only compound , trans -amide structure, exhibits sulfur—nitrogen close contact sulfurane-like trigonal bipyramidal geometry about sulfur r (S⋯N) = 2.780(1)A; θ(OS⋯N) 171.0(1)°). The interatomic distances (SO) 1.501(1) (OS⋯N) 4.281(1) are in agreement the usual SO double bond S⋯N rather than OSN hypervalent bonds. Owing to bulky -acetyl group, amide part ring of has cis structure nitrogen atoms lying 4.045(2) apart.