Actually there are more.
One can start with pseudoephedrine, from here there are the following reagent sets that can be used:
Iodine and red phosphorus, forming phosphorus triiodide in situ, along with a little water added, forming HI. PI3 iodinates the hydroxyl group on pseudoephedrine, and HI reduces it, reforming the HI and PI3 and eventually, when quenched and the PI3 hydrolyzed, the red phosphorus can be recovered, its a catalytic cycle although quite complex in its deeper mechanics. At higher temperatures, an aziridine can form also, which would be toxic, but aziridines ain't stable fellas at all, and its also broken down by heat into methamphetamine. But primary reduction mode is reduction of the intermediate iodo(pseudo)ephedrine by HI, using the red phosphorus as a means of catalytically reforming and recycling the HI/PI3 until the reduction has completed and the PSE (pseudoephedrine) is reduced to methamphetamine,
HP3O3, phosphorous acid and iodine can be used, as well as HP3O2, hypophosphorus acid and iodine in a similar sort of thing, although I've less knowledge of these routes, and I've never used either phos acid or hypo as reductant.
Then there is the Birch-Benkeser reduction. This involves first forming a solution of 'solvated electrons' in anhydrous ammonia, or other amine solvents of low boiling point, which act to complex the metal atom, where an alkali metal or alkaline earth metal (usually battery lithium, although personally I rate sodium as preferable since Li is an aggressive reducing agent, the Birch per se uses sodium, the Birch-benkeser uses lithium metal, and the typical use of the birch-B is to reduce a phenyl ring to a cyclohexadiene, but in the case of a benzylic alcohol like pseudoephedrine, and an additional proton source, typically by supplying the PSE substrate to the reaction as a slurry in an alcohol, it'll reduce the benzylic -OH to the hydrocarbon. IMO preferable to the phosphorus-iodine type routes because its a low temperature reaction, (anhydrous ammonia condenses at just short of -40 'C, a few degrees higher, something like 37 'C or so, and the alkali metal is added, forming an electride complex and 'free' solvated electrons only loosly bound to the complex, and therewith performing the reduction (reduction is gain of electrons, oxidation is loss, ) its cleaner, its very fast (minutes rather than a 24-48 hour long wet reflux, at least in the case of the red phos-iodine reduction its best done long and wet, aka the LWR, rather than shorter, faster and hotter, that way more byproducts are formed. All the methods starting from PSE give purely D-methamphetamine.
Then there is catalytic reduction with hydrogen gas and a precious metal catalyst of such things as chloro- or bromoephedrine, conversion to a tosylate and catalytic hydrogenation for reduction, very clean, but only available to those few who are highly skilled and who can prepare the apparatus, operate it safely, prepare the catalysts.
Again, D-meth is the outcome. D-meth, the dextrorotatory stereoisomers, are the ones carrying the dopamine releasing properties, laevo-meth is not recreational, and is indeed in the US sold in 'vicks' inhalers for nasal congestion without rx, certainly used to be, don't live there so don't know if they cracked down on it out of stupidity.
Then there is P2NP (1-phenyl-2-beta-nitropropene)
This and its reduction methods to amphetamines, is more versatile, and capable of producing more than just meth, can be used for straight up unsubstituted amphetamine, N-ethylamphetamine.
Can be reduced directly using lithium aluminium hydride or alternatively, although I've had no luck myself, at all, is using mercuric chloride-aluminium amalgam reduction directly from P2NP to amphetamine.
Synthesis of P2NP is via knoevanagel (Henry) condensation of benzaldehyde and nitroethane, using a primary, or some secondary amines as the acetate salts or using glacial acetic acid as rxn solvent; this can be done using either regular heating in a steam or hot water bath for some 6 hours or so, or else it can be done to a superior standard of purity using preformed amine acetate catalyst and utilizing microwave irradiation with careful monitoring of temperature. A better phenylnitropropene can be had, purity wise, using the microwave irradiation method of heating and preformed amine acetate catalyst at a closer to neutral PH. This can be done with microwaves in 20 minutes or even less for smaller batches.
P2NP can also be reduced either first using borohydride to reduce the double bond and giving 1-phenyl-2-beta-nitropropAne from the nitropropEne, and once a saturated nitroalkane chain is obtained either 80 degrees 'C for 2.5 hours with overhead (magnetic is out since it uses iron dust) stirring, fine iron powder and either hydrochloric or glacial acetic acid and some ferric chloride, which will give amphetamine, provided the borohydride reduction of the double bond is done first. If not the result is the versatile P2P, 1-phenyl-propan-2-one, phenylacetone, BMK (stands for benzylmethylketone) and this can be used either with various reducing agents plus an amine in anhydrous alcohol, such as methylamine for methamphetamine, ethylamine for N-ethylamphetamine etc., if the iron/acid/ferric chloride reduction is used without borohydride first to reduce the double bond, you get a reduction and rearrangement to the ketone, P2P.
For amphetamine from P2P-react with hydroxylamine salts (HCl 1-1 mol ratio sulfate needs twice that) and a base like sodium acetate or sodium carbonate to deprotonate the hydroxylammonium salt, and give hydroxylamine base in-situ, this forms the corresponding ketoxime of phenylacetone, which can be reduced using sodium metal in solution in anhydrous ethanol, for meth, various reductive aminations, Al-Hg amalgams and methylamine, acidic Al-Hg and nitromethane or nitroethane to in-situ form the amine and reductively aminate the phenylacetone to the corresponding amphetamine, although this process is dirty, uses toxic mercury (II) salts, nasty ass shit, its extremely exothermic, its bulky, not great for scale-up of batch sizes and it can take off like a bloody rocket and launch itself out of the condenser, even using a 2 meter condenser stack and two separate coolant feed lines with ice-salt-methylated spirits-water or CaCl2 solution with or without antifreeze to keep the condensers COLD. Really don't like Al-Hg at all personally and have had naff all luck with it.
For PSE reductions, I favour the birch type reductions conducted using instead of anhydrous, cryogenic liquefied ammonia gas, a constant stream of NH3 gas (anhydrous) bubbled through diethyl or diisopropyl ether, within which are suspended flakes or chips or other fine little shreds of lithium or preferably, personally due to less tendency towards over-reduction to the cyclohexadiene or even dearomatization with Li in excess to the aliphatic cyclohexane ring, giving something called propylhexedrine, an active stimulant but not as desirable nor as potent or as smooth as methamphetamine in comparison.
For P2NP, borohydride then acidic Fe/FeCl3 reduction works well. For P2P-amphetamine via the ketoxime or reductive amination via, well, any number of ways to skin that particular cat. And then there are all sorts of more exotic methods like Grignard organomagnesium based chemistry, oxymercuration-demercuration routes, even cadmium or thallium (II) based routes (no thank YOU, mercury is nasty as, organothallium or organocadmium? fuck that, fuck that right off up the ass with a ten foot pole and I'd still not do it for ANY pay. No. Just no fucking way. Organofucking thallium or cadmium reagents? jesus H christ. I'd rather shoot myself in the face, it'd at least be quicker and less of a horrible way to die.
