Reaction of 1,1,2,2-tetrabromoethane with triethyl orthoformate

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“…In contrast, activated ROH might also attack the positively polarized iodide or bromine atom of 1 (X = I, Br), resulting in the formation of intermediate C and ROI or ROBr. In 2006, Gazizov and coworkers11 reported a similar debromoalkoxylation reaction with the formation of unstable EtOBr. Intermediate C would transform into phosphaisocoumarin 1 (X = H) by proton transfer, which could undergo the subsequent alcoholysis reaction.…”

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

“…Furthermore, the tetraarylstibonium salt could catalyze the deprotection of the acetals into their corresponding aldehydes in aqueous media. 182 In 2009, Kharkongor and Myrboh presented a convenient and efficient one-pot method for the synthesis of a-ketoacetals Aromatic aldehyde acetals (189) 185,186 were synthesized via double debromoalkoxylation of dibromomethylarenes (187) with trialkyl orthoformate (4, 5) using ZnCl 2 (10 mol%) under solvent-free conditions at 80 C (Scheme 52). This reaction was promoted by the reaction of dibromomethylarenes (187) with an excess of (4, 5) to form a-brominated ether intermediates (188) which underwent a second debromoalkoxylation in the presence of an excess of (4, 5) to provide acetal (189) and the removal of 2 moles of alkyl bromide and 3 moles of formate ester.…”

“…182 In 2009, Kharkongor and Myrboh presented a convenient and efficient one-pot method for the synthesis of a-ketoacetals Aromatic aldehyde acetals (189) 185,186 were synthesized via double debromoalkoxylation of dibromomethylarenes (187) with trialkyl orthoformate (4, 5) using ZnCl 2 (10 mol%) under solvent-free conditions at 80 C (Scheme 52). This reaction was promoted by the reaction of dibromomethylarenes (187) with an excess of (4, 5) to form a-brominated ether intermediates (188) which underwent a second debromoalkoxylation in the presence of an excess of (4, 5) to provide acetal (189) and the removal of 2 moles of alkyl bromide and 3 moles of formate ester. 186 In 2006, Gazizov et al investigated the reaction of TEOF with 1,1,2,2-tetrabromoethane with different molar ratios at 180 C under solvent-free conditions within 10 h. It was found that dehydrobromination reaction took place via the reaction of triethyl orthoformate with 1,1,2,2-tetrabromoethane in 1 : 2 molar ratios to obtain tribromoethylene, ethyl formate, ethyl bromide, and ethanol as the main products along with low amounts of ethyl acetate and dibromoethylene.…”

“…On the other hand, the debromination reaction was accomplished via the reaction of substrates in a 2 : 1 molar ratio to give ethyl formate, ethyl bromide, dibromoethylene, ethyl hypobromite, and acetal. 187 …”