765-56-0Relevant articles and documents
Organic reactions in the solid state: Reactions of enclathrated 3,4- epoxycyclopentanone (= 6-oxobicyclo[3.1.0]hexan-3-one) in Tri-othymotide and absolute configuration of 4-hydroxy- and 4-chlorocyclopent-2-en-1-one
Gerdil, Raymond,Liu, Huiyou,Bernardinelli, Gerald
, p. 418 - 434 (1999)
Several aspects of the heterogeneous actions of aqueous and gaseous HCl on the chemical behavior of 3,4-epoxycyclopentanone (=6- oxablcyclo[3.1.0]hexan-3-one; 1) included in the asymmetric cages of tri-o- thymotide (TOT) clathrates belonging to space groups P3121 are described, showing specific features strikingly at variance with those observed in liquid solutions. In a first step, the substrate underwent an acid-promoted allylic isomerization, as already observed in our previous investigations, to give optically active 4-hydroxycydopent-2-en-1-one (2). In a Consecutive step, a displacement of the OH group was accomplished by the Cl- anion to afford the corresponding chloro compound 3. Polymorphism was encountered in the preparation of TOT/1 clathrates. Recrystallization of TOT in the pure guest 1 yielded micro-twinned crystals belonging to the P31 space group (host/guest ratio 1: 1), whereas the expected P3121 lattice grew from a mixture of TOT, 1 and MeOH. The structural determination of TOT/1 was carried out by X-ray diffraction (Fig. 1). Kinetic measurements were achieved that shed light on some striking features of this type of heterogeneous reactions for solid-liquid and solid-gas systems. Several reactions of pure clathrate antipodes (+)-TOT/1 with gaseous HCl were carried out under various conditions; concentration and enantiomer-excess(ee) determinations of the products 2 and 3 allowed to establish a larger ee for 3, thus demonstrating the influence of the host-guest diastereomeric association on the progression of the reaction. The correlation of optical activities of the host and products for the global reaction disclosed the sequence (+)-(M)-TOT/1 → (- )-2 → (-)-3. A new way for the preparation of 2 was devised. It was further demonstrated that the X-ray structure analysis of the chiral clathrate (M)- TOT/(+)-2 (Fig. 4) associated with chitoptical measurements was an efficient and straightforward method to determine the absolute (+)-(R)-configuration of the guest. The enantioselectivity of the TOT clathrate for 2 was established by two different methods which allowed the appraisal of an accurate revised value of the specific rotation of 2. The enclathration of 3 occurred exclusively in the orthorhombic centrosymmetric host lattice Pbca, thus prohibiting the X-ray structural determination of the guest absolute configuration. The problem of finding a pathway to the intended enantiomer enrichment of 3 was worked out through the action of aqueous HCI on microcrystalline (+)-TOT/(-)-(S)-2 that gave an optically active mixture of unreacted 2 with 3 as sole product. The pure optically active 3 was isolated by Subsequent TLC. The resolution of 3 was achieved by GC over a chiral column and its (unknown) specific rotation measured. The absolute configuration of 3 was established by the measurement of the enantiomer purity of the optically active mixture 3 obtained after the total conversion of (-)-(S)-2 in the presence of thionyl chloride in Et2O, dioxane, and benzene. It was deduced that the (-)-3 enantiomer had the (S)-configuration.
Prostaglandin Endoperoxide Model Compounds. Part 2. Stereospecific Synthesis of Isomeric 5-Bromo-2,3-dioxabicycloheptanes and 2-Bromo-6,7-dioxabicyclooctanes
Bloodworth, A. J.,Eggelte Henny J.
, p. 3272 - 3278 (2007/10/02)
Cyclopent-3-enyl hydroperoxide (9) has been prepared from cyclopentadiene via hydroboration and autoxidation, and converted by bromination into trans-3,cis-4-dibromocyclopentyl hydroperoxide (10).Reaction of compound (10) with silver oxide has afforded endo-5-bromo-2,3-dioxabicycloheptane (11) (42percent), whereas treatment of compound (10) with silver trifluoroacetate has provided exo-5-bromo-2,3-dioxabicycloheptane (15) (6percent) and exo-5-trifluoroacetoxy-2,3-dioxabicycloheptane (16) (14percent).The exo-bromide (15) (11percent) has also been prepared from cyclopent-3-enyl bromide by trans-hydroperoxybromination and ring closure with silver oxide.The configurations of the peroxides have been confirmed by catalytic hydrogenation.Cyclohex-3-enyl hydroperoxide (26) has been prepared from anisole by a 5-step procedure ending with oxidation of N-cyclohex-3-enyl-N'-tosylhydrzide, and converted by bromination into a mixture of two diastereoisomeric 3,4-dibromocyclohexyl hydroperoxides.Treatment of the trans-3,cis-4-dibromide (27) with silver oxide has afforded endo-2-bromo-6,7-dioxabicyclooctane (29) (40percent), whereas reaction of the cis-3,trans-4-dibromide (28) with silver trifluoroacetate has provided exo-2-bromo-6,7-dioxabicyclooctane (30) (18percent).Treatment of compound (27) with silver trifluoroacetate yielded a 9:1 mixture of peroxides (30) and (29) (19percent), but compound (28) did not react with silver oxide.It is suggested that the silver oxide-induced dioxabicyclizations proceed by an SN2 mechanism whereas the silver trifluoroacetate reactions involve a bromonium ion intermediate.
CONVERSION OF 3-CYCLOPENTENYL HYDROPEROXIDE INTO 5-SUBSTITUTED-2,3-DIOXABICYCLOHEPTANES
Bloodworth, A. J.,Eggelte, H. J.
, p. 2001 - 2004 (2007/10/02)
3-Cyclopentenyl hydroperoxide 8 has been prepared from cyclopentadiene via hydroboration and autoxidation.Bromination of 8 followed by treatment with an appropriate silver salt has afforded the 5-substituted-2,3-dioxabicycloheptanes 11 (endo-bromo), 13 (exo-bromo), and 12 (exo-trifluoroacetoxy).
