A stereoselective synthesis of conjugated dienes from alkynes via the hydroboration-iodination reaction

Stereospecific Couplings of Secondary and Tertiary Boronic Esters

“…[81][82][83] These examples showed that aryl and alkylboranes can undergo arylation processes by treatment with electronrich aryllithiums (e.g., 2-lithiofuran, 2-lithiothiophene) followed by electrophilic trapping (Scheme 21). The mechanism of these coupling reactions is analogous to the Zweifel olefination reaction [84] and comprises a sequence of electrophilic aromatic substitution, 1,2-metallate rearrangement, and elimination [85,86] from the in situ formed aryl-substituted boronate complex. A more detailed mechanistic discussion is presented later.…”

Selective uni- and bidirectional homologation of diborylmethane

“…5). Its subjection to standard Matteson homologation, 25 Zweifel olefination 26 and standard oxidation conditions gave the corresponding difunctionalisation products 36–38 , respectively, in good yield. We were also particularly interested in whether selective functionalisation of either the primary or the tertiary boronic ester could be achieved.…”

Stereospezifische Kupplungen von sekundären und tertiären Boronsäureestern

“…2‐Lithiofuran, 2‐Lithiothiophen) und anschließende elektrophile Abfangreaktionen Arylierungsprozesse eingehen können (Schema ). Der Mechanismus dieser Kupplungsreaktionen entspricht dem der Zweifel‐Olefinierung84 und umfasst eine Sequenz aus elektrophiler aromatischer Substitution, 1,2‐Metallatumlagerung und Eliminierung85, 86 aus dem in situ gebildeten arylsubstituierten Boronatkomplex. Eine detailliertere mechanistische Betrachtung folgt später.…”