TABLE 1.

Structural definition of compounds based on Figure 1

Name	Compound #	R1	R2	R3	R4	R5
Fentanyl	1	Ethyl	H	H	α-H, β-H	Phenyl
Cyclopropyl fentanyl	2	Cyclopropyl	H	H	α-H, β-H	Phenyl
p-Methyl cyclopropyl fentanyl	3	Cyclopropyl	p-Methyl	H	α-H, β-H	Phenyl
Cyclobutyl fentanyl	4	Cyclobutyl	H	H	α-H, β-H	Phenyl
Cyclopentyl fentanyl	5	Cyclopentyl	H	H	α-H, β-H	Phenyl
Furanyl fentanyl	6	2-Furanyl	H	H	α-H, β-H	Phenyl
Tetrahydrofuran fentanyl	7	2-Tetrahydrofuranyl	H	H	α-H, β-H	Phenyl
Acetyl fentanyl	8	Methyl	H	H	α-H, β-H	Phenyl
o-Methyl acetyl fentanyl	9	Methyl	o-Methyl	H	α-H, β-H	Phenyl
α-Methyl acetyl fentanyl	10	Methyl	H	H	α-Methyl, β-H	Phenyl
Acryl fentanyl	11	Ethylene	H	H	α-H, β-H	Phenyl
o-Fluoro acryl fentanyl	12	Ethylene	o-Fluoro	H	α-H, β-H	Phenyl
p-Fluoro acryl fentanyl	13	Ethylene	p-Fluoro	H	α-H, β-H	Phenyl
Isobutyryl fentanyl	14	Isopropyl	H	H	α-H, β-H	Phenyl
o-Fluoro isobutyryl fentanyl	15	Isopropyl	o-Fluoro	H	α-H, β-H	Phenyl
m-Fluoro isobutyryl fentanyl	16	Isopropyl	m-Fluoro	H	α-H, β-H	Phenyl
p-Fluoro isobutyryl fentanyl	17	Isopropyl	p-Fluoro	H	α-H, β-H	Phenyl
p-Chloro isobutyryl fentanyl	18	Isopropyl	p-Chloro	H	α-H, β-H	Phenyl
Pivaloyl fentanyl	19	Tert-butyl	H	H	α-H, β-H	Phenyl
Butyryl fentanyl	20	Propyl	H	H	α-H, β-H	Phenyl
o-Fluoro butyryl fentanyl	21	Propyl	o-Fluoro	H	α-H, β-H	Phenyl
Methoxyacetyl fentanyl	22	Methoxy methylene	H	H	α-H, β-H	Phenyl
o-Fluoro fentanyl	23	Ethyl	o-Fluoro	H	α-H, β-H	Phenyl
m-Fluoro fentanyl	24	Ethyl	m-Fluoro	H	α-H, β-H	Phenyl
p-Fluoro fentanyl	25	Ethyl	p-Fluoro	H	α-H, β-H	Phenyl
o-Methyl fentanyl	26	Ethyl	o-Methyl	H	α-H, β-H	Phenyl
m-Methyl fentanyl	27	Ethyl	m-Methyl	H	α-H, β-H	Phenyl
p-Methyl fentanyl	28	Ethyl	p-Methyl	H	α-H, β-H	Phenyl
p-Chloro fentanyl	29	Ethyl	p-Chloro	H	α-H, β-H	Phenyl
Cis-3-methyl fentanyl	30	Ethyl	H	Cis-methyl	α-H, β-H	Phenyl
Trans-3-methyl fentanyl	31	Ethyl	H	Trans-methyl	α-H, β-H	Phenyl
Furanylethyl fentanyl	32	Ethyl	H	H	α-H, β-H	2-Furan
β-Hydroxy thiofentanyl	33	Ethyl	H	H	α-H, β-OH	2-Thiophene
β-Methyl fentanyl	34	Ethyl	H	H	α-H, β-methyl	Phenyl