Key features of the β-isocupreidine (β-ICD)-catalyzed asymmetric Baylis–Hillmanreaction of aldehydes with 1,1,1,3,3,3-hexafluoroisopropyl acrylate (HFIPA) are presented. In addition, an improved method using azeotropically dried β-ICD is described.
Complementary chemistry! α‐Isocupreine (α‐ICPN) was synthesized for the first time in one step fromquinine by treatment with CF3SO3H (see scheme). This compound serves as an enantiocomplementarycatalyst to β‐isocupreidine (β‐ICD) in the Morita–Baylis–Hillman reaction.
互补化学!通过CF 3 SO 3 H处理,从奎宁一步一步合成了α-异cupreine(α-ICPN)(参见方案)。在Morita-Baylis-Hillman反应中,该化合物可作为β-异cupreidine(β-ICD)的对映体互补催化剂。
A Bifunctional β-Isocupreidine Derivative as Catalyst for the Enantioselective Morita-Baylis-Hillman Reaction and a Mechanistic Rationale for Enantioselectivity
作者:Gianluca Martelli、Mario Orena、Samuele Rinaldi
DOI:10.1002/ejoc.201200405
日期:2012.8
Starting fromβ-isocupreidine (β-ICD), a series of difunctional catalysts were synthesized to ascertain their usefulness in the asymmetric Morita–Baylis–Hillman (MBH) reaction. The trichloroacetylcarbamate derivative was found to give the (R)-MBH adducts in excellent optical purities (90–99 % ee) and moderate to good yields (43–83 %), in some cases, better than β-ICD. A number of acrylates were also
9R)-3,9-Epoxy-6'-hydroxy-11-norcinconane (23), a pseudoenantiomer of β-isocupreidine (β-ICD), was synthesized starting with a fragmentation reaction of 10-bromo-10,11-dihydroquinine, prepared fromquinine. Baylis-Hillman reaction of benzaldehyde with 1,1,1,3,3,3-hexafluoroisopropyl acrylate (HFIPA) using 23 as a chiral amine catalyst gave the corresponding S-enriched adduct in high optical purity (93%