Preparation of formaldehyde and acetaldehyde acetals

Abstract

General Procedure for the Preparation of 4 and 7. To a stirred solution of methylenetriphenylphosphorane [prepared from methyltriphenylphosphonium bromide (5.71 g, 16 mmol) and n-BuLi (10.67 mL of 1.5 M hexane solution, 16 mmol) in THF under ice cooling] was added a solution of 3 (or 6) (13.6 mmol) in THF (30-60 mL) under ice cooling. The mixture was warmed

Synthesis of X(Y)-(EO)n-OCH3 Type Heterobifunctional and X(Y)-(EO)n-Z Type Heterotrifunctional Poly(ethylene glycol)s

“…A low temperature is needed because the boiling point of both diethyl ether and ethyl vinyl ether are about 36 °C and the reaction is exothermic . Acetal interchange from EE ethers to acetaldehyde acetals may happen during heating in acid according to a previous report; thus, TsOH must be removed completely by washing with saturated NaHCO 3 solution before distillation. The successful synthesis was confirmed by 1 H NMR and elemental analysis (see Supporting Information).…”

Synthesis of heterobifunctional poly(ethylene glycol)s by an acetal protection method

“…The successful synthesis was confirmed by NMR and elemental analysis. 1 H NMR (ppm) (CDCl 3 ): 1.17 interchange to happen, which will result in the formation of side products (acetaldehyde acetals), 9 TsOH must be removed completely by washing with saturated NaHCO 3 solution prior to distillation. We used diphenylmethyl potassium (DPMK) as a base for generating alkoxide initiators.…”

Convergent Synthesis of Pyragonicin

“…A facile rearrangement of the MOM group seems to be due to the neighboring group participation of a 1-or 2-hydroxyl group to the intermediary cation (i) (Figure 2). Although formyl acetals 21 Compound 3 was prepared from known compounds (8 and 20 22 ) in three steps. The epoxide 20 reacted with lithium iodide 23 in the presence of acetic acid to give iodohydrin, which was silylated to provide silyl ether 7 in 75% yield from 20 (Scheme 3).…”