α-Lithiobenzyl ethers, generated by selective α-lithiation, undergo an aldol-Tishchenko reaction upon treatment with carboxylic esters and paraformaldehyde. The reaction of the organolithium with the carboxylate generates an intermediate enolate that, after formaldehyde addition, affords 1,2,3-triol derivatives in a straightforward and one-pot manner. These products are obtained as single diastereoisomers
The reductive cleavage of aromatic dimethylacetals and ketals, 1, with Li metal in THF at low temperature allows the generation of stable α-alkoxy-α-arylsubstituted carbanions, avoiding the Wittig rearrangement. Reaction of these carbanions with various electrophiles afforded the expected products 2. Further in situ reaction of compounds 2 afforded the products of reductive electrophilic disubstitution
-mediated dehydrogenative crossed aldol condensationreaction of acyclic aliphatic ethers with benzaldehyde dimethyl acetal to give specifically indene derivatives or α,β-unsaturated carbonylcompounds has been found. When the ethers have bis(β-alkylethyl) ether structures, dehydrogenative formation of enol ether equivalents followed by successive crossed aldol addition to acetal-originated electrophile
Boron Trifluoride Etherate Mediated Dehydrogenative Nucleophilic Addition Reaction of Aliphatic Ethers in the Presence of Acetal Affording α,β-Unsaturated Carbonyl Compounds
In the presence of borontrifluoride etherate, some kinds of aliphaticethers have been found to react with benzaldehyde dimethyl acetal yielding α,β-unsaturated carbonyl compounds with evolution of H 2 . In this reaction,dehydrogenation of the ether undergoes in cooperation with the acetal and BF 3 , which enables the ether molecule to behave as enol ether equivalent affording crossed aldol adduct
在三氟化硼醚合物的存在下,已发现某些脂肪族醚与苯甲醛二甲缩醛反应生成 α,β-不饱和羰基化合物,同时放出 H 2 。在该反应中,醚的脱氢与乙缩醛和 BF 3 共同发生,这使得醚分子表现为烯醇醚等价物,通过亲核攻击由缩醛形成的氧碳鎓离子亲电试剂提供交叉羟醛加合物。