Solid-Acid Catalysed Rearrangement of Cyclic α,β-Epoxy Ketones

Abstract

Various cyclic α,β‐epoxy ketones rearranged to α‐formyl ketones and/or vic‐diones in the presence of catalytic amounts of zeolites and montmorillonite K10. This provides an excellent alternative to conventional homogeneous systems with respect to yields and workup. Differences in product distribution and type of products in the rearrangement of pulegone oxide could be reasonably explained by invoking different pathways for homogeneous and heterogeneous catalysts.

Biocidal Compounds from Mentha sp. Essential Oils and Their Structure–Activity Relationships

“…Structural determination was carried out by GC/MS, 1 H-and 13 C-NMR analysis and the results (included as Supporting Information) were in agreement with previous reports. [36] [37] Synthetic Procedures Synthesis of Piperitenone. Piperitenone (4) was prepared as previously reported.…”

“…Isolated and synthesized compounds were analyzed by GC/MS, 1 H-and 13 C-NMR and their spectral data were validated by previously reported data 2, [14] [40] 3, [42] 5, [14][36] 8 [43] and 10, [10] [37] with the exception of compound 6 for which no available data were found in the literature. Data for compound 6 are provided here while for known compounds 2, 3, 5, 8, and 10 are given in the Supplementary Information of this paper.…”

Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones

“…Mechanistic considerations, for the later reaction, involve an initial ketonic decarboxylation, followed by the attack of an unstable carbanion to the second carboxyl group, leading to the cyclopentanone 15. (R)-2,2,5-trimethylcycloheptane-1,3-dione (17) was obtained in high yield (90%) by a BF 3 $Et rearrangement from pulegone oxide [40]. Also, the cis and trans stereomers of methyl and phenyl (R)-pulegone derivatives 22a, 22b, 21a and 22b were easily prepared by conjugated addition of Me 2 CuLi and PhMgBr/CuI respectively, as previously described in the literature [41,42].…”

“…The synthetic route includes the initial conversion of (S)-perillaldehyde (30) in allylic alcohol 38. Subsequent epoxidation of 38 to 39 followed by oxidative cleavage afforded (S)-3-isopropylhexanedioic acid (40) [43,44]. In the next step, diacid 40 was heated at 350 C in the presence of a catalytic amount of Na 2 CO 3 to give 13 in 35% general yield from (S)-perillaldehyde (30).…”

“…The crude product 39 (1.37 g) was used without any further purification in the next step. (40). To a stirred solution of epoxide 39 (1.3 g, 7.5 mmol) in 37 mL of THF-H 2 O (10:1) at 0 C was added H 5 IO 6 (3.65 g, 16 mmol) in one portion.…”