Camphor-derived thioureas: Synthesis and application in asymmetric Kabachnik-Fields reaction

Synthesis of α-Aminophosphonates and Related Derivatives; The Last Decade of the Kabachnik–Fields Reaction

“…2-Cyclopropylpyridimidine-4-carbaldehyde ( 40 ) was also used as the starting material in three-component condensations. In one case, phosphomolybdic acid was applied as the catalyst ( Scheme 34 ) [ 57 ]; in another, camphor-derived thiourea organocatalysts ( 42, 43 ) were utilized ( Scheme 35 ) [ 58 ]. The yields of products ( 41 ) were mostly high.…”

Zirconium-catalyzed asymmetric Kabachnik–Fields reactions of aromatic and aliphatic aldehydes

“…Finally, Reddy and coworkers reported the use of the bis-thiocarbamate catalyst 29 to give the -aminophosphonate 30 from the aldehyde 28 in low enantioselectivity. 17 To summarize, the existing methods for the asymmetric catalytic Kabachnik-Fields reaction work well only for aromatic aldehydes. The only two examples with aliphatic aldehydes comes from the work of Nakamura and Shibata who were able to prepare the -aminophosphonate 23 from cyclohexanecarboxaldehyde and isovaleraldehyde in 61% and 31% ee, respectively.…”

Enantioselective Hydrophosphonylation of in Situ Generated N-Acyl Ketimines Catalyzed by BINOL-Derived Phosphoric Acid

“…Prominent asymmetric approaches toward α-amino phosphonates include resolution, chiral auxiliary-based processes, and various enantioselective approaches . The most direct and easy strategy is the enantioselective addition of phosphite to aldimines (commonly known as aza-Pudovik reaction). , Another attractive approach for the construction of the C–P bond is the direct catalytic asymmetric Kabachnik–Fields reaction . In contrast, enantioselective synthesis of quaternary derivatives via functionalized ketimines remains elusive, due to their lower reactivity than aldimines and difficulty in enantiofacial discrimination .…”