316801-41-9Relevant academic research and scientific papers
Pd-catalyzed reactions of donor - Acceptor-substituted cyclopropanes and their ring-opened derivatives: Attempted heck cyclization and novel one-pot enolate arylations
Khan, Faiz Ahmed,Czenvonka, Regina,Reissig, Hans-Ulrich
, p. 3607 - 3617 (2007/10/03)
Donor-acceptor substituted cyclopropane derivatives 4a-g were synthesized in good yields from ketones, via the corresponding silyl enol ethers 2a-g, by cyclopropanation with methyl diazoacetate followed by alkylation using o-iodobenzyl iodide. The γ-oxo esters 5a-g were prepared in high yield, employing NEt3·3 HF. A novel Pd-catalyzed one-pot transformation of 4a-f into 1,2-disubstituted indanes 6a-f was accomplished using either CsF (Method A or B) or Bu4NF (Method C) as the fluoride source to achieve the in situ ring-opening of 4a-f. The two reagents CsF and Bu4NF function in a complementary manner. For example, CsF works better with enones 4b and 4c, while Bu4NF functions well with aryl/alkyl ketones 4d-f. Pd-catalyzed Heck cyclization of vinyl ketone 5a furnished mainly the 7-exo-trig cyclization product 7 but isopropenyl ketone 5b gave a moderate yield of indane derivative 6b, arising from enolate arylation. When the carbonyl group in 5b was protected, a novel tricyclic compound 13 was obtained in low yield. Wiley-VCH Verlag GmbH, 2000.
