Synthesis of natural fragrancejasminaldehyde using silica-immobilized piperazine as organocatalyst

Abstract

Jasminaldehyde (α-pentyl cinnamaldehyde) is a natural fragrance that can be produced via aldol-type C–C bond formation between heptanal and benzaldehyde. The use of bases like NaOH to form jasminaldehyde typically leads to significant waste and by-product formation. To provide sustainable options with diminished waste formation and high conversions and selectivities, herein a silica-immobilized piperazine is used as organocatalyst for the jasminaldehyde synthesis either in bio-based solvents (e.g. 2-methyltetrahydrofuran, 2-MeTHF) or in solvent-free conditions (using neat substrates as reaction media). Under reported conditions, a production of ∼7 g jasminaldehyde L⁻¹ h⁻¹ is observed, delivering on-spec conversions and selectivities (>90% each). Selectivity remains unaltered during catalyst recycling, whereas a loss of conversion is significantly observed after reusing the catalyst for several cycles.