I also want to explore other hydrogen donors than ammonium formate in CTH.
How about exploreing some unlisted hydrogen donors.
:P
Nice piece of work :)
Keep em comin!
Foxy
https://www.thevespiary.org/rhodium/Rhodium/chemistry/nitrostyrene.nabh4.reduction.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/nitrostyrene.nabh4.reduction.html)
The nitroalkane from the rxn above was used.
4,7 g (22mmol) 1-(2,5-dimethoxyphenyl)-2-nitroethane was dissolved in 50ml EtOH and this solution was poured into flask containing 200mg 5%Pd/C and a stirbar. 1,6g (42mmol) NaBH4 was dissolved in 5ml water and 10ml EtOH, this solution was added in portions of 1-2ml over 20min to the nitroalkane solution. The temp was maintained at 20 deg by immersion in a cold water bath. After the addition was complete the mixture was allowed to stir for 1 hour. Diluted HCl was added dropwise until gas evolution ceased and then further until pH 2 was reached. Two teaspoons of celite was added and stirred for one minute then everything was filtered at the water pump. The ethanol was removed in a rotovap and the aqueous solution was extracted with DCM (2x25ml) then basified with 50% NaOH soln until pH 12 and extracted again with 2x25ml DCM. The alkaline DCM extractions was dried with MgSO4 and the solvent removed in a rotovap. The residue was a oil with a yellow color. This oil was dissolved in 50ml diethylether and dry HCl in IPA added until pH 4 was reached. The crystals was filtred off and dried until constant weight.
Yield 1,4g (29%) 2C-H*HCl
Identity confirmed by HPLC
This simple reduction works but it has to be adjusted to achieve better yields. Let´s combine our efforts and we will have two simple routes to 2C-H from the nitrostyrene using no LAH.
You are the researcher of the month Barium!
This is from Synthesis pp713-714, 1987:
Reduction of Aliphatic and Aromatic Nitro Compounds with Sodium Borohydride in Tetrahydrofuran Using 10 % Palladium-on-Carbon as Catalyst
General Procedure
A 100 mL two-necked flask equipped with reflux condenser and stirred is charged with the nitro compound (10 mmol) in THF (40 mL). The solution is cooled by an ice bath and 10 % palladium on carbon (0.4 g) is added. NaBH4 (25 mmol) is then added in three portions over 10 min, the ice bath is removed, and stirring is continued at room temperature for 20-30 min. Excess NaBH4 is decomposed with 2normal hydrochloric acid (till pH = 6) and Et2O (70 mL) is added. The solid is filtered off and the filtrate is washed with H2O (2x15 mL) and dried (MgSO4). The solvent is evaporated to give the 95-98 % pure amine.
Yields for primary and secondary nitroalkanes are 70-80 %.
//Tyrone Slothrop
Post 318550 (https://www.thevespiary.org/talk/index.php?topic=11968.msg31855000#msg31855000)
(Barium: "TMA-2", Novel Discourse): By using ethyl acetate to destroy excess alanate you are probably ethylating at least a part of your amine (actually this is a known route to produce methyl-ethyl-tryptamines). There are at least two independent papers out describing this effect.Only the nitroethenes dimerize uncontrollably.
Excellent, thank you!
-SpicyBrown