Synthesis of (±)-Pentacycloanammoxic Acid Methyl Ester

Key words

(±)-pentacycloanammoxic acid methyl ester - C₂₀-fatty acid methyl ester - [4+2] cycloaddition - [2+2] photo-cycloaddition - N₂ extrusion - Wolff rearrangement

Significance

In 2004, Corey and Mascitti reported the first synthesis of the C₂₀-fatty acid methyl ester of (±)-pentacycloanammoxic acid which was isolated from anammoxic microbe ­Candidatus Brocadia anammoxidans in 2002. It is characterized by five anti-fused cyclobutanes. Key transformations are [4+2] cycloaddition, [2+2] photocycloaddition, N₂ extrusion, and Wolff rearrangement.

Comment

[4+2] Cycloaddition of B to dibromide A, obtained from cyclooctatetraene via bromination, resulted in tricyclic dibromide C. Two successive reductions of tricycle C gave cyclobutene D. [2+2] Photocycloaddition of D to 2-cyclopentenone gave pentacyclic ketone F. Photochemical N₂ extrusion reaction of azo-bridged G resulted in ketone H which was converted into α-diazo ketone J in two additional steps. Photo-Wolff rearrangement of J gave as a 3:1 mixture of endo- and exo-methyl esters L. (±)-Pentacycloanammoxic acid methyl ester was obtained from K in six additional steps.

Publication History

Article published online:
17 September 2021