Reaction of 2-(1,3-butadienyl)magnesium chloride with carbonyl compounds and epoxides. A regioselectivity study

Preparation of 1,3-dienyl organotrifluoroborates and their Diels–Alder/cross-coupling reactions

“…The conditions were optimized by employing 1.8 to 2 equivalents of Grignard reagents to minimize the side reactions (<5%). It was also observed that the iodo-substituted diene (43) reacted faster than the corresponding bromo-diene (44) as expected. But with higher amounts of external Grignard reagent (1.8 or greater) the bromo-diene could also be converted in a similar fashion.…”

“…42 We chose to prepare the butadiene initially and used a route that involved preparing the Grignard reagent of chloroprene (26), 43 We have also prepared the tetra n-butylammonium (TBA) salt of the BF 3 substituted diene (29) (85%). 46 TBA salts of other trifluoroborates have been shown to improve cross coupling yields considerably, presumably due to their greater organic solvent solubility.…”

“…Phenyl substituted halo dienes (43)(44)(45) were directly generated from the corresponding allenic alcohol (41) using the established protocol of Ma et al 49 We found that the temperature of the rearrangement reaction has significant impact on the product yield for the formation of the iodo-substituted diene (43). In the presence of 1.5 mol% Pd catalyst the reaction could be performed at 40°C for both the bromo-and chloro-substituted dienes (44,45).…”

“…Newly formed halo-dienes (43)(44)(45) were first subjected to the protocol (used for formation of the unsubstituted 2-BF 3 diene (27)) to attempt to prepare the corresponding BF 3 -substituted dienes. The first step was to generate the corresponding Grignard reagent followed by addition of trimethoxy borate and quenching by KHF 2 /H 2 O.…”

Synthesis and radical ring-opening polymerization of vinylcyclopropanes bearing vinylsilane groups

“…Chloroprene was obtained from Du Pont-Showa Denko Co., Ltd. Ethyl diazoacetate 4 and trimethylsilylbutadiene 5 were synthesized according to the reported methods. …”