Glutaconaldehyde

Abstract: Recent results from our laboratory have prompted us to introduce a modification of the original Baldwin proposal for the biosynthesis of manzamine alkaloids. In this new model, aminopentadienal derivatives of general structures 2 or 3 can not only cyclize to give pyridinium salts such as cyclostellettamines but also react with 5,6-dihydropyridinium salts 1 leading to species such as 6 or 7, which would be key intermediates in the syntheses of manzamine A and halicyclamine B. On the basis of the chemistry depicted in Scheme 2, model reactions of dienes 9, 10, 12, and 13 with salts 1 have been investigated. Diene 9 gave an interesting rearrangement product 15a, while dienes 10 and 12 gave halicyclamine- and manzamine-type adducts 19 and 23, respectively. In addition, glutaconaldehyde derivative 13 gave adduct 32 possessing some characteristic features of sarain A.

Abstract: Syntheses of 5-halogeno-2,4-dienals 1a–c are described starting either from the glutaconaldehyde potassium salt or from furan. The 5-bromopenta-2,4-dienal 1b can be transformed efficiently into homologous ω-bromo polyenals 2–4, precursors of ω-bromo polyenol ethers 5b,d, 6 and 7. After bromine–lithium exchange, followed by condensation with carbonyl compounds, 1-bromo-6-methoxyhexa-1,3,5-triene 5b, 1-bromo-8-methoxyocta-1,3,5,7-tetraene 6 and 1-bromo-10-methoxydeca-1,3,5,7,9-pentene 7 lead to various conjugated tri-, tetra- and penta-enals in good yields, in a one-pot procedure.

Abstract: 5-Bromopentadienal 1b(n= 2), easily obtained from the potassium glutaconaldehyde salt, is used as precursor of ω-bromoheptatrienal 1d, ω-bromomethoxyhexatriene 2, diene diols 4, diene diones 5, 1,6-dibromohexa-1,3,5-triene 6 and 1,8 triene diol 8, of controlled configuration.

Abstract: N-tert-Butylimino derivatives of aldehydes were deprotonated with LDA and reacted with vinamidinium chloride to give 2-alkylaminopentadienimine derivatives, which were isolated as their corresponding hydrochloride in 68-81% yield. Reaction of these derivatives with ammonium acetate or salts of primary amines, in n-butanol at 80 degrees C, afforded the corresponding 3-alkylpyridines or 3-alkylpyridinium salts in high yield. Alkaline hydrolysis of 2-alkylaminopentadieneimine derivatives allowed a practical accesss to potassium salts of 2-alkylglutaconaldehyde.