Palladium-Catalyzed Regioselective Intermolecular Hydroalkoxylation of 1-Arylbutadienes

Abstract

An efficient method for the synthesis of (E)-(3-alkoxybut-1-enyl)­benzenes by Pd-catalyzed regioselective intermolecular hydroalkoxylation of 1-arylbutadienes has been developed. This method can be executed in a simple operation with no dry reaction conditions required and having tolerance to a wide range of substrates. Chloromethyl methyl ether (MOMCl) as an additive was found to be essential for the success of the reaction.

Mn(I)-Catalyzed Carbon-Skeleton Rearrangement of Tertiary Alcohol-Based Aldol Reaction with Aldehydes

“…Wittig Reaction of Ketone 3−1 with MeP + Ph 3 Br − . 19 To a suspension of methyltriphenylphosphonium bromide (0.30 mmol, 1.5 equiv) in THF (2 mL), n-BuLi (0.30 mmol, 1.5 equiv) was added at 0 °C under argon. After stirring for 15 min, 3−1 (63 mg, 0.20 mmol, 1.0 equiv) was added.…”

Catalytic Asymmetric Hydroalkoxylation and Formal Hydration and Hydroaminoxylation of Conjugated Dienes

“…As unprotected allyl alcohols , and allyl hydroxylamines , are ubiquitous skeletons and building blocks in medicinal, material, and agrochemistry, asymmetric hydration and hydroaminoxylation of conjugated dienes are highly valuable routes for furnishing motifs with corresponding free hydroxyl or aminoxyl units. Although transition-metal-catalyzed asymmetric hydrofunctionalizations of conjugated dienes have received considerable attention , and a group of transition metals, including Pd, − Ni, − Rh, − Co, − and Cu, have been demonstrated to stereoselectively catalyze the formation of allylic C–C, C–N, C–S, C–P, C–Si, and C–B bonds, the catalytic system for the construction of C–O bonds has not been elucidated (Scheme a), that is, all types of O-based nucleophiles, including abundant alcohols, − phenols, carboxylic acids, water, hydroxylamine, oxime, and so forth, are not suitable for this enantioselective hydrofunctionalization process. Only the use of allenes and alkynes, which are significantly more reactive electrophilic substrates, has received a few successes. − …”

Asymmetric Hydroxymethylative Etherification of 1,3-Dienes with Isatins and Alcohols via Pd(0)-π-Lewis Base Catalysis

“…In recent years, TM-mediated enantioselective hydroalkoxylation of C–C multiple bonds emerged as a more atom- and step-economic protocol for the production of allylic ethers, since it allowed net addition of alcohols to readily accessible allenes or alkynes straightforwardly . As the latest effort, He and Yang successfully extended the hydroalkoxylation strategy to abundant 1,3-dienes, via asymmetric palladium and nickel catalysis, respectively (Scheme a). , Although elegant advances have been achieved, the hydroalkoxylation of unsaturated hydrocarbons has mainly generated simple allylic ether derivatives. It would be highly facilitating but challenging that alkoxyl groups and another privileged pharmacophore rather than simple hydrogen could be simultaneously installed into C–C multiple bonds of simple starting materials, especially in a catalytic diastereo- and enantioselective manner.…”