The beta orientation at C-9 is preserved through selective protection/deprotection sequences. Epimerization is avoided by using non-basic conditions and low-temperature reactions.
Assessment indicates the process is [carbon neutral/low emission]. the synthetic ep 4 beta by carbon link
Instead of attaching an omega side chain via an ester or amide bond, a palladium-catalyzed cross-coupling reaction (e.g., Suzuki-Miyaura or Negishi coupling) is employed. A vinyl iodide or triflate intermediate is coupled with an organozinc or organoboron reagent bearing the omega chain. This step directly forges a C-C bond, creating the eponymous carbon link. The beta orientation at C-9 is preserved through