4-(Dimethylamino)pyridine (DMAP) is a nucleophilic catalyst frequently used for the acylation of alcohols and the rearrangement of O-acylated enolates. Due to the need for an enantioselective version of this catalyst, Gregory Fu π-complexed the heterocycle with a metal and added a 2-substituent to the ring.[1]: 5577 This resulted in a planar chiral set of enantioselective DMAP analogs.[2]
As of 2018,[update][3] at least two such catalysts were commercially available: DMAPC5Ph5, a 1,2,3,4,5-pentaphenylferrocene-fused DMAP derivative, and PPY*, a 1,2,3,4,5-pentamethylferrocene-fused 4-pyrrolidinylpyridine derivative.[1]: 5578 [2]: 542–543 A drawback of these catalysts is their limited production volume, as the 1996 synthesis route produces a racemate, requiring resolution via chiral HPLC.[4] In 2020, a high-yield enantioselective synthesis of the two commercial catalysts, amongst other ferrocene-fused 4-dialkylaminopyridines, was achieved.[4][5]
References
edit- 1 2 Wurz, Ryan P. (1 December 2007). "Chiral Dialkylaminopyridine Catalysts in Asymmetric Synthesis". Chemical Reviews. 107 (12): 5570–5595. doi:10.1021/cr068370e. PMID 18072804.
- 1 2 Fu, Gregory C. (2004-08-01). "Asymmetric Catalysis with "Planar-Chiral" Derivatives of 4-(Dimethylamino)pyridine". Accounts of Chemical Research. 37 (8): 542–547. doi:10.1021/ar030051b. ISSN 0001-4842.
- ↑ "Metal Catalysts for Organic Synthesis including Organocatalysts" (PDF). Strem Chemicals. 2018. pp. 76, 79.
- 1 2 Bernardo, Olaya; González‐Pelayo, Silvia; López, Luis A. (18 March 2022). "Synthesis and Applications of Ferrocene‐Fused Nitrogen Heterocycles". European Journal of Inorganic Chemistry. 2022 (8). doi:10.1002/ejic.202100911.
- ↑ Yoshida, Kazuhiro; Liu, Qiang; Yasue, Risa; Wada, Shiro; Kimura, Ryosuke; Konishi, Takuma; Ogasawara, Masamichi (3 January 2020). "Versatile and Enantioselective Preparation of Planar-Chiral Metallocene-Fused 4-Dialkylaminopyridines and Their Application in Asymmetric Organocatalysis". ACS Catalysis. 10 (1): 292–301. doi:10.1021/acscatal.9b04438.