A new route to γ-substituted γ-lactones and δ-substituted δ-lactones based on the regioselective β-scission of alkoxyl radicals generated from transannular hemiacetals
✍ Scribed by Kazuhiro Kobayashi; Akiyoshi Sasaki; Yoshikazu Kanno; Hiroshi Suginome
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- French
- Weight
- 695 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Abstmct -A new general synthesis of y-subshtuted y-lactones and Gsubstltuted &lactones including dlhydro-5 octyl-2(3H)-furanone, a natural pheromone, 1s described The synthesis involves the regloselectlve j3-sclsslon of alkoxyl ra&cals generated from transannular hemlacetals as the key step Substituted "I-and 6-lactones have recently attracted conslderable attention, mamly because molecules of this class include many natural products that reveal slgmficant blologlcal actlvlty 2 A variety of methods for syntheslzrng this class of molecules have recently been developed 3*4 In our previous papers,5 we reported on a new short-step general synthesis of uobenzofuran-1(3H)-ones (phthahdes) and its 3-subsmuted denvattves based on a double p-scissIon of alkoxyl radrcals generated from lethyl-l, 2-dlhydrobenzocyclobuten-1-01s and 1.2-catacondensed 1,2-dlhydrocyclobuten-l-ols, respecnvely The mechamstlc conslderatlons regarding the route from 1,Zcatacondensed 1,2-dlhydrocyclobuten-1-01s to the phthahdes led us to develop a second new method for the general synthesis of 3-substnuted phthahdes, which IS outlmed m Scheme 1 Thus, the phtolysls of the hypomdnes of 1,3-dlhydro-1,3-alkanolsobenzofuran-l-01s (2), obtainable from acychc and cychc 1,4-drones (1) and alkylmagneslum halides, m benzene contammg mercury(I1) oxide and &me gives 3-(3-mdopropyl)phthahdes (3)