A New Synthesis of the Thiazole Fragment of Vitamin B₁¹

Room-Temperature Total Hydrogenation of Biomass-Derived Furans and Furan/Acetone Aldol Adducts over a Ni–Pd Alloy Catalyst

“…To get more insight into the mechanistic aspect, hydrogenation of 2-methylfuran is performed over monometallic Pd nanoparticles under optimized reaction conditions, resulting in the formation of product 1b . These findings are in accordance with the previous reports suggesting that the ring opening presumably occurs via the hydrodeoxygenation of furfuryl alcohol over the Pd surface. − Interestingly with the Ni 0.90 Pd 0.10 alloy nanoparticles, any such open chain products (such as 1b ) are not observed and only the desired product 1a remains the dominating product, even after extending the reaction time to 24 or 48 h. The above observations suggest that the presence of Ni in the NiPd alloy may presumably play a crucial role in achieving a high selectivity toward ring hydrogenation over hydrodeoxygenation, presumably by tuning the interaction of furfuryl alcohol with the catalyst surface. Further, the facile hydrogenation of the furan ring over Pd nanoparticles is also in accordance with previous reports, which suggest that the strong interaction of hydrogen with the Pd surface and low activation barrier for H 2 dissociation on the surface of Pd presumably makes Pd to catalyze hydrogenation reactions even at room temperature. − Furthermore, a favorable interaction of the furan ring to the Pd catalyst surface may also contribute in a facile hydrogenation under mild reaction conditions. ,, In this regard, Li et al also reported an efficient hydrogenation of furans (2-furfuryl alcohol) to total hydrogenated products (tetrahydro-2-furfuryl alcohol) over Pd nanoparticle-based catalysts under room-temperature conditions using H 2 gas at atmospheric pressure in 2-propanol.…”

“…In contrast to Ni 0.90 Pd 0.10 , monometallic Pd nanoparticles also result in the furan ring opening to produce 5-hydroxypentan-2-one ( 1b ) in 39% selectivity along with the desired product furfuryl alcohol ( 1a , selectivity 61%) in 6 h (Table , entry 4). The ring opening of compound 1 to 1b over the Pd surface might be due to the multiple catalytic reactions involving hydrodeoxygenation of furfuryl alcohol to 2-methylfuran followed by furan ring opening to 1b , which is in accordance with previous reports. − Moreover, DFT calculations for furan hydrogenation and ring opening over the Pd(111) surface suggested that hydrofuran is a reactive intermediate for both hydrogenation as well as ring opening pathways to form the respective tetrahydrofuran and ring opening products . A study suggested that furan ring opening is thermodynamically favored, while ring hydrogenation is kinetically driven, and hence tetrahydrofuran is formed as a major product at a low temperature.…”

Millimeter- and submillimeter-wave spectroscopy of thioformamide and interstellar search toward Sgr B2(N)

“…The synthesis of Londergan et al (1953) has been modified to obtain a formamide-free sample. In a 500 mL three-necked flask equipped with a mechanical stirrer and a thermometer, we introduced 300 mL of dry tetrahydrofuran and formamide (30 g, 0.667 mol).…”

Synthesis of 2-methylproline and 2-methylornithine

“…Anal. (CeHuN02) C, , N. 5-Methyl-5-(3-nitropropyl)hydantoin (5). The procedure and equipment were the same as for 1.…”