Chemistry of salicylic acid and anthranilic acid. I. Reduction of methyl salicylate, methyl anthranilate and their derivatives with sodium borohydride.

Silane Reduction of 5-Hydroxy-6-methyl-pyridine-3,4-dicarboxylic Acid Diethyl Ester: Synthesis of Vitamin B6

“…These conditions afforded at best a 50-54% isolated yield of vitamin B 6 free base and up to 18% of the intermediates. These partially reduced products were either characterized by comparison to known compounds, lactone ( 9 ) [ 56 ], or observed in GC/MS experiments, mono reduced ( 10 ) ( Figure 1 ). Based on another publication [ 57 ], Bu 4 NF was replaced by the combination of 10 mol% CsF and 20 mol% 18-crown-6 ether.…”

Photochemical Synthesis of the Bioactive Fragment of Salbutamol and Derivatives in a Self‐Optimizing Flow Chemistry Platform

“…The methyl protecting group of 7 was first cleaved into the corresponding phenol with BBr 3 at −78 °C in CH 2 Cl 2 (62 % yield). The presence of a phenol adjacent to the methyl ester enabled the reduction of the latter to proceed by refluxing the substrate in THF in the presence of NaBH 4 [17] . The resulting crude 2‐hydroxybenzyl alcohol was highly water‐soluble and was hence eventually protected, without intermediate isolation, into final compound 1 with acetone/2,2‐dimethoxypropane 1 : 1 and a catalytic amount of p ‐toluenesulfonic acid at room temperature.…”

“…The presence of a phenol adjacent to the methyl ester enabled the reduction of the latter to proceed by refluxing the substrate in THF in the presence of NaBH 4 . [17] The resulting crude 2hydroxybenzyl alcohol was highly water-soluble and was hence eventually protected, without intermediate isolation, into final compound 1 with acetone/2,2-dimethoxypropane 1 : 1 and a catalytic amount of p-toluenesulfonic acid at room temperature. These last steps (ester reduction and ketal protection) afforded target compound 1 in 58 % isolated yield as a stable lipophilic solid, the NMR data of which matched those of the literature (Supporting Information).…”

Synthesis of Functionalized 4H‐3,1‐Benzoxazines through Chemoselective Reduction of Benzoxazin‐4‐Ones

“…We thus realized that DIBAL‐H could be used for a chemoselective carbonyl reduction of 2‐pyrazolyl‐benzoxazin‐4‐one derivatives 1a–d , and found that all substrates were uniformly converted to the corresponding benzyl alcohols 2a–d in a good yield (Table ). Although it has been reported the reduction of benzoxazin‐4‐ones takes place either at the carbonyl or imino groups depending upon the substituents at 2‐position, the present result clearly shows DIBAL‐H reduced only the carbonyl group . This is likely due to the presence of an electron‐rich and/or sterically hindered pyrazole ring, which exerts a favorable influence on the reduction of the carbonyl group.…”