Economics suggests that if there were an easier, cheaper synthetic path with available ingredients, they'd be using it now.
The pseudoephedrine-to-meth synthesis is the most direct; it uses a variant of the Birch Reduction to reduce the -OH group on sudofed- that is all it takes.
None of the curent methode were used 30 years ago.
There are two chemical engineering geniuses in the federal Slam right now who develop these processes in their heads since they are not allowed pencil and paper, much less reference works and suplies. They are people who could have top jobs in industry if they weren't natural born criminals.
Developing the new methods is their way of 'sticking it to the man' but it is certainly not easy and they aren't going to expend the effort until it is needed.
I haven't got the references to them offhand, and don't have time to look.
So9
The Birch reaction is also called the Nazi Method since it was the one used in Germany during WWII- it's been used for way longer than 30 years.
It was the availability of metallic lithium that made it possible in the US within the last couple of decades.
Most of the other syntheses were worked out around 1938, check the reference "Der Beilstein" or the patent files.
http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/amphetamine.reduction.html
Here are a bunch of reactions. Most require either restricted chemicals, or such things as powdered platinum or palladium.
Below are the List 1 and List 2 chemicals restricted by DEA under the Comprehensive Methamphetamine Control Act. Some of these are problems to just industry or agriculture, but some like Acetone,potassium permanganate, or toluene are things regular folks might buy. I've seen MEK and MiBK in hardware stores. I'd imagine that if you bought enough, or regularly, you'd wind up on a watch list of some sort. Pseudoephedrine is just the tip of the iceberg as far as government control goes, I'm afraid.
(1) Anthranilic acid, its esters, and its salts
(2) Benzyl cyanide
(3) Ephedrine, its salts, optical isomers, and salts of optical isomers
(4) Ergonovine and its salts
(5) Ergotamine and its salts
(6) N-Acetylanthranilic acid, its esters, and its salts
(7) Norpseudoephedrine, its salts, optical isomers, and salts of optical isomers
(8) Phenylacetic acid, its esters, and its salts
(9) Phenylpropanolamine, its salts, optical isomers, and salts of optical isomers
(10) Piperidine and its salts
(11) Pseudoephedrine, its salts, optical isomers, and salts of optical
isomers
(12) 3,4-Methylenedioxyphenyl-2-propanone
(13) Methylamine and its salts
(14) Ethylamine and its salts
(15) Propionic anhydride
(16) Isosafrole
(17) Safrole
(18) Piperonal
(19) N-Methylephedrine, its salts, optical isomers, and salts of optical
isomers (N-Methylephedrine)
(20) N-Methylpseudoephedrine, its salts, optical isomers, and salts of optical isomers
(21) Hydriodic Acid
(22) Benzaldehyde
(23) Nitroethane
(24) Gamma-Butyrolactone (Other names include: GBL; Dihydro-2 (3H)-furanone; 1,2-Butanolide; 1,4-Butanolide; 4-Hydroxybutanoic acid lactone; gamma-hydroxybutyric acid lactone)
(25) Red Phosphorus
(26) White phosphorus (Other names: Yellow Phosphorus)
(27) Hypophosphorous acid and its salts
(including ammonium hypophosphite,
calcium hypophosphite,
iron hypophosphite,
potassium hypophosphite
manganese hypophosphite
magnesium hypophosphite
and sodium hypophosphite
(b) List II chemicals:
(1) Acetic anhydride
(2) Acetone
(3) Benzyl chloride
(4) Ethyl ether
(5) Potassium permanganate
(6) 2-Butanone (or Methyl Ethyl Ketone or MEK)
(7) Toluene
(8) Hydrochloric acid (including anhydrous hydrogen chloride)
(9) Sulfuric acid
(10) Methyl Isobutyl Ketone (MIBK)
(11) Iodine