Highly Enantioselective Intramolecular Morita‐Baylis‐Hillman Reaction Catalyzed by Mannose‐Based Thiourea‐phosphine

Abstract

The saccharide‐based chiral bifunctional thiourea‐phosphines were developed as chiral organocatalysts for the intramolecular Morita‐Baylis‐Hillman reaction of ω‐formyl‐enones. With only 2 mol% of thiourea‐phosphine catalyst 3c, chiral functionalized cyclohexenes were achieved under mild reaction conditions with excellent yields and enantioselectivities.

Enantioselective Cyanosilylation of α,α‐Dialkoxy Ketones by Using Phosphine‐Thiourea Dual‐Reagent Catalysis

“…In our previous work on Morita–Baylis–Hillman reaction, the phosphine‐thiourea with an additional chiral group could enhance the enantioselectivity, and there was a chirality match between the chiral backbone and the additional chiral group . The same effects were observed when the diastereomer C5 and C6 were used as catalyst for the model reaction (entries 5 and 6 vs. entry 4, Table ).…”

The Application of Biocatalysis in the Preparation and Resolution of Morita‐Baylis‐Hillman Adducts and Their Derivatives

“…This work was extended to include saccharide-based thio-urea phosphines that proved extremely effective at catalysing enantioselective ring-closing MBH reactions to give cyclohexene derivatives. [38] More recently Gao et al [39] developed a chiral phosphine 10, quite similar to that developed by Wu, [37] and used it in the asymmetric aza-MBH reaction between indole-derived sulfonyl imines 11 and bis-(3-chlorophenyl)methyl acrylate 12, and obtained the desired products 13 in good yields and enantioselectivities ranging from 76-97 % ee (Scheme 5).…”

“…It is interesting to note that replacement of the thiourea with urea resulted in only trace amounts of product. This work was extended to include saccharide‐based thio‐urea phosphines that proved extremely effective at catalysing enantioselective ring‐closing MBH reactions to give cyclohexene derivatives [38] …”

Phosphine-Catalyzed Asymmetric Organic Reactions

“…254 More recently, Wu and co-workers further enhanced the above intramolecular MBH reaction by using mannose-based thiourea−phosphines. 255 Chen and co-workers studied the intramolecular MBH reaction of dicarbonyl compound 454 by using a ferrocenebased phosphine−squaramide P112 (Scheme 139). 256 Good yields and high enantioselectivities were attainable for a wide range of substrates, except for substrates bearing 2-Br and 2-Cl on the aryl ring.…”