THE PREPARATION OF METHYL, ETHYL, PROPYL, AND BUTYL ORTHOCARBONATES¹

Nonpeptide angiotensin II receptor antagonists. Synthesis and biological activity of benzimidazolecarboxylic acids

“…30% ethanolic HC1 (3 mL), and EtOAc (3 mL) was stirred at room temperature for 1 h. The reaction mixture was concentrated in vacuo and the residue was diluted with MeOH and aqueous NaHCOg. The precipitate was collected by filtration and recrystallized from CHClg-MeOH to give 5a (0.30 g, 77%) as yellow needles: mp 140-141 °C; 1H NMR (DMSO-dg) 3.84 (3 H, s), 4.26 (2 H, m), 6.86 (1 H, t, J = 7.9), 7.46 (2 H, d, J -8.4), 7.54-7.65 (4 H, m), 7.79 (1H, dd, J = 1.4 and 7.7), 7.95 (1H, dd, J = 1.4 and 7.7), 8.05-8.11 (2 H, m), 8.67 (1 H, t, J = 5.5); IR (KBr) 4b by the similar procedures for the preparation of 5a, in overall 53% yield as a yellow syrup: NMR (CDCla) 3.61 (3 H, s), 3.89 (3 H, s), 4.21 (2 H, d, J = 4.8), 6.72 (1 H, d, J = 8.0), 7.30 (4 H, m), 7.36 (1 H, dd, J = 1.1 and 7.3), 7.42 (1 H, dd, J = 1.6 and 7.4), 7.53 (1 H, dd, J -1.6 and 7.5), 7.82 (1 H, dd, J -1.4 and 7.6), 8.00 (1 H, dd, J -1.7 and 8.3), 8.10 (1 H, dd, J -1.8 and 7.8); IR (neat) 3310, 1730,1690 cm*1.…”

“…Each of the esters 33a-c was detritylated with 1 N HC1, and the structure of each product was assigned by NOE difference spectra. Irradiation of the benzyl protons at 6 at 7.98 (dd, J = 0.7 and 1.6 Hz), and the NOE also extended to the doublet of H-3 and H-5 in the biphenyl part. By contrast, irradiation of the benzyl protons at 5.27 in 34b, the 5-carboxylate isomer, resulted in enhancement of the H-7 proton which appeared at 7.49 (dd, J = 0.7 and 8.4 Hz).…”

Ethyl Orthocarbonate

“…The above procedure is essentially that of Tieckelmann and Post. 3 Ethyl orthocarbonate has been prepared by the reaction of chloropicrin and sodium ethoxide by Bassett 4 and Röse. 5 Thiocarbonyl perchloride has been reported 3,6 to react with sodium ethoxide to give good yields of ethyl orthocarbonate.…”

Ortho Esters

“…When R' = N0 2 [108-110a] or SCI [109], the tetraalkyl orthocarbonates are obtained. When R' = halogen, mainly orthoformates are formed except for the recent case describing the reaction of polyfluoroalkanols with carbon tetrachloride catalyzed by ferric chloride to give polyfluoroalkyl orthocarbo nates [110b,c] (Eq.…”