Aldol condensations on a 3-alkylidene-2,5-diketopiperazine - synthesis of two marine natural products
Peer reviewed, Journal article
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- Department of Chemistry 
Original versionSynlett : Accounts and Rapid Communications in Synthetic Organic Chemistry. 2018;29(10):1303-1306 https://doi.org/10.1055/s-0036-1591755
The synthesis of two marine natural products containing a 3-alkylidene-6-arylidene-2,5-diketopiperazine scaffold by employing two consecutive aldol condensations starting with 1,4-diacetyl-2,5-diketopiperazine is reported. The target compounds contain a phenol or an imidazole group as aryl substituents, respectively, and suitable conditions for the aldol condensation of 1-acyl-3-alkylidene-2,5-diketopiperazine with the required functionalised aromatic aldehydes were developed. Provided the optimal base was used, introduction of the phenol group did not require use of a protecting group. Boc-protection was beneficial for introduction of the imidazole group, and conditions for carrying out the aldol condensation and Boc-deprotection in one step were identified. The stereochemistry of the target compounds was confirmed by NMR analysis.