Table 1.

¹⁸O-labeling study of amide synthesis from α-bromo nitroalkanes

Entry*	NO2 label (% N)	H2O (%18O)	Atmosphere	Amide (% 18O)	Δ18O	Yield† (%)
1‡	0	> 99	open	< 1	< 1	75
2‡	82	0	open	17	−65	76
3§	82	0	open	49	−33	70
4§	82	> 99	open	49	−33	70
5§	82	0	Ar	66	−16	70
6	0	0	¶	83	+83	68

^*Reactions employed one equivalent of α-bromo nitroalkane (0.2 M in THF), with N-iodosuccinimide (one equivalent) added as the final reagent at 0 °C. “Open” atmosphere refers to use of a static atmosphere provided by a cap or septum. Other variations used a balloon of the indicated gas. Isotopic distribution determined by high resolution mass spectrometry.

^†Isolated yields.

^‡1.2 equivalents of amine used.

^§Five equivalents of amine used to replace potassium carbonate base.

^¶97% enriched gas used.