TABLE 3.

Summary of isotope labeling results for NOV2

Compound	16O2-H218O system		18O2-H216O system
	16O-Labeled	18O-Labeled	16O-Labeled	18O-Labeled
4-HBA	98.7%	1.3%	4.5%	95.5%
3,5-DHBA	92.2%	7.8%	21.9%	78.1%
			(24.1%)a	(75.9%)a
			(35.1%)b	(65.9%)b

^a Reaction products were dried by argon stream after a 2-min reaction.

^b Reaction products were dried by SpeedVac method after a 2-min reaction.