Indanone ring opening

Hgdroxylamine hydrochloride potassium hydroxide Indanone ring opening s. U, 256... 

Thiopyrans have, in general, been less thoroughly investigated. The isothiochroman-4-one (245) on irradiation in basic methanol is converted to the indanone (246)199 a pathway involving electrocyclic ring opening and the formation of the intermediate (247) may be implicated. An alternative... 

Irradiation of 2,5-dimethylbenzoyl oxiranes results in formation of p-hydroxy functionalized indanones (74) that structurally resemble biologically active pterosines. Nanosecond laser flash photolysis and quantum-chemical calculations based on density functional theory support a photoenolization mechanism.Reversible photochemical transformations of cis- and tra v-2,3-dimethyloxirane radical cations in freonic matrices at 77 K has been observed and explained by the interconversion between the open (C2-C3 broken) and the cyclic forms. Photocatalytic ring opening of a-epoxy ketones in cyclopentanone, using 2,4,6-triphenylpyrylium tetra-fluoroborate as electron acceptor, results in the diastereoselective formation of 2,5-dioxaspiro[4,4]nonanes through Ca-O bond cleavage and subsequent nucleophilic attack by cyclopentanone to the radical cation intermediates. ... 

Asymmetric intramolecular addition/ring opening reaction of 3-(2-borylphenyljcyclobutanones afforded 1-indanones having chiral benzylic quaternary carbon centers by enantioselective P-carbon elimination (Scheme 3.18) [30]. 

Asymmetric ring-opening reorganization of cyclobutanol 42 proceeded via 1,4-rhodium migration to give 1-indanone 43 in a diastereo- and enantioselective manner (Scheme 3.24) [35]. 

Furthermore, this strategy was applied successfully in the enantioselective synthesis of alcyopterosin I (28), which has a 6-6-5 ring system, as well as for the bicyclic alcyopterosins N (30) and C (31) (Scheme 7.7) [12], The latter became available through a selective ring opening of the ether tether in 28 to provide the indanone 29. Notably, the efficiency of the synthetic sequences leading to the alcyopterosins is not only the result of a powerful rhodium-catalyzed intramolecular [2 + 2 -f 2]... 

The route employed to prepare indanone 51 involved the cycloaddition-hydrolysis-aldol sequence shown in Scheme 3.9. Accordingly, condensation of cyclopentenone 52 with ynamine 53 (84) afforded the bicyclic enamine 54 which was converted to indanones 51 and 55 by hydrolytic cyclobutane ring opening followed by intramolecular aldol condensation. Interestingly, treatment of 54 with aqueous formic acid yielded indanone 51 which has stereochemistry complementary to that at C(15) and C(20) in reserpine. In contrast, hydrolysis of this substance with aqueous hydrochloric acid afforded the trans-fused indanone 55. Subsequent to this work, the Ficini group found that esterification of 51 followed by photochemically induced addition of methanol afforded adduct 56 which has four of the reserpine stereocenters in place (23). While no further work on this problem has been reported, these preliminary investigations demonstrate a novel use of [2 -h 2] photocycloaddition chemistry in potential approaches to yohimbane alkaloid synthesis. 

Homologation of an alkyl chain and alteration of ring size are also useful approaches in analog design. Therefore, 3 / ,4 l -di-0-( )-camphanoyl-2, 2 -dimethylnaphtho[5,6-fl]pyran (125), 3 /f,4 /f-di-0-(—)-camphanoyl-2, 2 -dimethyl-dihydropyrano[2,3-e]-l-indanone (DCl, 126), and three compounds with opened A ring (127-129) were designed and synthesized. These compounds vary... 

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