There are plenty of unscheduled opioids out there, it just takes some work to fin d them in papers or patents and knowledge which one is a winner.
Morphine and all of it's 3,6-diesters and other esters of morphine or codeine (which include morphine diacetate aka diacetylmorphine/diamorphine or 'Heroin', morphine dinicotinate aka dinicotinoylmorphine/nicomorphine or 'Vilan' -all (or most) of the 3,6-diesters of morphine are morphine prodrugs). Other esters of morphine include desomorphine,
The 1912 Convention had made its control measures applicable "To all new derivatives of morphine, of cocaine, or of their respective salts, and to every other alkaloid of opium, which may be shown by scientific research, generally recognized, to be liable to similar abuse and productive of like ill-effects."
Although I'd love to find an unscheduled codeine derivate, it seems like they've got all the basis covered. I am looking at acetyldihydrocodeine and trying to see how we can manipulate that to make something unscheduled. Acetyldihydrocodeine is a derivative of dihydrocodeine, and both are converted into dihydromorphine. Our best bet are nitazene-opioids or a ketobemidone or dextromoramide derivatives or analogues.
21 U.S. Code § 802 subsection 17 :
Subparagraphs A, B, C, D, E, F state:
(A) Opium, opiates*, derivatives of opium and opiates, including their isomers, esters, ethers, salts, and salts of isomers, esters, and ethers, whenever the existence of such isomers, esters, ethers, and salts is possible within the specific chemical designation. Such term does not include the isoquinoline alkaloids of opium.
(B) Poppy straw and concentrate of poppy straw
(C) Coca leaves, except coca leaves and extracts of coca leaves from which cocaine, ecgonine, and derivatives of ecgonine or their salts have been removed.
(D) Cocaine, its salts, optical and geometric isomers, and salts of isomers.
(E) Ecgonine, its derivatives, their salts, isomers, and salts of isomers.
(F) Any compound, mixture, or preparation which contains any quantity of any of the substances referred to in subparagraphs (A) through (E).
* includes morphine, diamorphine, nicomorphine, desomorphine, codeine, heterocodeine, and related substances
21 U.S. Code § 813 subsection 32 - Treatment of controlled substance analogues
Subparagraphs A, B, C
(A) Except as provided in subparagraph
(C), the term “controlled substance analogue” means a substance —
I: the chemical structure of which is substantially similar to the chemical structure of a controlled substance in schedule I or II;
II: which has a stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I or II; or
III: with respect to a particular person, which such person represents or intends to have a stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I or II.
(B) The designation of gamma butyrolactone or any other chemical as a listed chemical pursuant to paragraph (34) or (35) does not preclude a finding pursuant to subparagraph
(A) of this paragraph that the chemical is a controlled substance analogue.
(C) Such term does not include —
I: a controlled substance;
II: any substance for which there is an approved new drug application;
III: with respect to a particular person any substance, if an exemption is in effect for investigational use, for that person, under section 355 of this title to the extent conduct with respect to such substance is pursuant to such exemption; or
IV: any substance to the extent not intended for human consumption before such an exemption takes effect with respect to that substance.
That enlarged part is the loophole.