Synthesis of 6-oxononanolides, 6- and 7-oxodecanolides and 7-oxoundecanolide via enamine reactions

Borowitz, Irving J.; Williams, G. J.; Gross, Leonard.; Rapp, Robert D.

doi:10.1021/jo01269a067

Cited by 52 publications

(3 citation statements)

References 3 publications

(3 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unusual side reactions have been reported previously in the epoxidation of enol ethers. The oxidation of substituted and unsubstituted tetrahydrochromans 4 with excess peroxy acid gives 6-ketononanolides 5 (17). Formation of 5 involves reaction of the initially formed epoxy ethers with excess peroxy acid to give hydroxy peroxy esters, which then fragment to 6-ketononanolides (Scheme II).…”

Section: Resultsmentioning

confidence: 99%

Preparation of aflatoxin B1 8,9-epoxide using m-chloroperbenzoic acid

Iyer¹,

Harris²

1993

Chem. Res. Toxicol.

View full text Add to dashboard Cite

Aflatoxin B1 is a potent carcinogen which requires activation in order to react with DNA. The exo-8,9-epoxide is putatively the active form although it has thus far eluded direct detection in biological systems. This laboratory has reported a synthesis of the epoxide using dimethyldioxirane as the oxidant [(1988) J. Am. Chem. Soc. 110, 7929-7931]. A new, very convenient synthesis is described herein in which m-chloroperbenzoic acid is used as the oxidant in a two-phase system. The reaction is carried out in CH2Cl2 in contact with an aqueous phosphate buffer (pH 7.2) to remove the byproduct m-chlorobenzoic acid, which would otherwise react with the epoxide. Excess m-chloroperbenzoic acid is removed with aqueous sodium thiosulfate.

show abstract

Section: Resultsmentioning

confidence: 99%

Preparation of aflatoxin B1 8,9-epoxide using m-chloroperbenzoic acid

Iyer¹,

Harris²

1993

Chem. Res. Toxicol.

View full text Add to dashboard Cite

show abstract

“…Mechanistically, such processes are sometimes closely related to the elimination‐type fragmentation reactions outlined in Section 3.1; indeed, the oxidation step is often simply a method by which an intermediate capable of undergoing Grob/Eschenmoser‐type fragmentation can be generated in situ . For example, upon treatment with meta ‐chloroperbenzoic acid, bicyclic enol ether 25 is converted into intermediate 26 , which can then go on to form ring‐expanded lactone 27 in one‐pot via the elimination of meta ‐chlorobenzoic acid . Alternatively, ozonolysis has also been used to cleave the alkene bridges in macrocycles, exemplified by the synthesis of Exaltone ® precursor 29 from alkene 28 .…”

Section: Fragmentation Reactionsmentioning

confidence: 99%

Ring‐Expansion Reactions in the Synthesis of Macrocycles and Medium‐Sized Rings

Donald

Unsworth

2017

Chemistry A European J

215

108

View full text Add to dashboard Cite

Functionalised macrocycles and medium-sized rings have applications in a number of scientific fields, ranging from medicinal chemistry and supramolecular chemistry, to catalysis and nanotechnology. However, their value in these areas can be undermined by a simple, but important limitation: large ring systems are very often difficult to make. Traditional end-to-end cyclisation reactions of long linear precursors are typically unpredictable and impractical processes, mainly due to unfavourable enthalpic and entropic factors. Most published methods to make large rings focus on minimising the damage inflicted by performing the difficult cyclisation step; in contrast, ring-expansion reactions enable it to be avoided altogether. In this Review article, it is highlighted how "growing" rings from existing cyclic systems via ring expansion can expedite the efficient, practical and scalable synthesis of macrocycles and medium-sized rings.

show abstract

“…The mechanism of cleavage of bicy clic tetrasubstituted olefins with MCPBA has been dis cussed earlier. 21 It was demonstrated 22 that 2 methyl 4,5,6,7 tetrahydrobenzofuran undergoes analogous cleav age with peroxy acids. An alternative mechanism involves the transformation of peroxy ester 11 into 1,2 dioxetane derivative 14 followed by is decomposition to give iso butyrate 12.…”

Section: Resultsmentioning

confidence: 99%

Study of plant coumarins 1. Transformations of peucedanin

et al. 2006

View full text Add to dashboard Cite

The structure of 2 bromooreoselon, which was prepared by bromination of peucedanin or oreoselon with molecular bromine, was established. The compositions and structures of the reaction products of this bromide with amines, such as pyridine, triethylamine, and morpholine, as well as with sodium acetate and potassium hydroxide were studied. The reaction of peucedanin with m chloroperoxybenzoic acid affords peuruthenicin isobutyrate.Coumarins produced by higher plants and fungi and those prepared by synthetic methods can serve as biologi cally active compounds of medical interest and, con cequently, have attracted considerable attention. 1-3 Furocoumarin containing drugs, which exert the photo sensitizing and photoprotective action, such as psoralen, isopsoralen, 8 methoxypsoralen, bergapten, and iso pimpinellin, are used in therapy of skin diseases. 4 4 Hydr oxycoumarin derivatives are used as anticoagulants. 4 Some plant coumarins hold considerable promise as antiviral (anti HIV) 5-8 and antitumor agents. 9-12Siberian flora is endowed with plants valuable as sources of coumarins. 13 Among these plants is, undoubt edly, Peucedanum (Peucedanum morisonii Bess., the Apiaceae or Umbelliferae family), which is widespread in Western Siberia. 14 Thirteen coumarin derivatives were identified in roots of this plant. 15 Furocoumarin peucedanin (1) can easily be isolated in a yield of 4% of the weight of the dry material. It is known that peucedanin sensitizes photohemolysis 16 and exhibits antitumor activ ity. 17 The pronounced biological activity and availability of peucedanin have stimulated our interest in studying its chemical properties.The aim of the present study was to synthesize peucedanin derivatives by modifications of the furan ring. Results and DiscussionBromination of peucedanin (1) with an equimolar amount of bromine has been reported 18 to afford mono bromide identical to that prepared by bromination of oreoselon (2) (the hydrolysis product of peucedanin) un der the same conditions (Scheme 1). However, the yields and the structure of this monobromide have not docu mented. We established the structure of the monobromide by comparing the 1 H NMR spectra of this compound and oreoselon. The fact that the spin spin coupling of the signal for the H atom bound to the tertiary C atom of the isopropyl group in the bromide is simpler (septet, J = 6.8 Hz) compared to the signal for the corresponding H atom in oreoselon (septet of doublets, J = 6.8 Hz, J = 4.0 Hz) indicates that the H(2) atom in the latter com pound is replaced by Br. Therefore, the monobromide under study is 2 bromooreoselon (2 bromo 2 (1 methyl ethyl) 7H furo[3,2 g][1]benzopyran 3,7 dione (3)). It was demonstrated that the yields of bromide 3 prepared by bromination of peucedanin and oreoselon with an equimolar amount of molecular bromine were 92 and 98%, respectively.We studied the behavior of bromide 3 in reactions with amines. Refluxing of 3 with pyridine in 95% ethanol af forded a quaternization product, viz., N {2 (1 methyl ethyl) 3,7 dioxo 7H fur...

show abstract

Synthesis of 6-oxononanolides, 6- and 7-oxodecanolides and 7-oxoundecanolide via enamine reactions

Cited by 52 publications

References 3 publications

Preparation of aflatoxin B1 8,9-epoxide using m-chloroperbenzoic acid

Preparation of aflatoxin B1 8,9-epoxide using m-chloroperbenzoic acid

Ring‐Expansion Reactions in the Synthesis of Macrocycles and Medium‐Sized Rings

Study of plant coumarins 1. Transformations of peucedanin

Contact Info

Product

Resources

About