2000 alkylation, arylation, dealkylation, dearylation, C-acylation, olefination

alkylation, arylation, dealkylation, dearylation, C-acylation, olefinationO 0280

15 - 061New Approaches to Olefin Cross-Metathesis. — Cross-metathesis(CM) of terminal olefins catalyzed by Grubb’s Ru catalyst is studied withvarying approaches. A two-step CM can be used for homologating terminalolefins to protected allylic alcohols, amines and esters in which the terminalolefins first undergo self-metathesis to give dimers and then undergo a secondCM with terminal olefins as is shown for (IV)/(V). The syntheses of novel aminoacid, carbohydrate and peptide homodimers such as (VII)/(VIII) confirm theexceptional functional group tolerance of the ruthenium catalyst. The CM ofterminal olefins containing an allylic methyl substituent like olefin (XII) showsa markedly improved (E)-selectivity compared with e.g. methyl-unsubstitutedolefin (Ia). In the course of studying the activity of substrates for CM with allylicoxygen functionality it is found that acrolein acetals such as (XIV) and (XVII)are robust and (E)-selective CM substrates. — (BLACKWELL, HELEN E.;O’LEARY, DANIEL J.; CHATTERJEE, ARNAB K.; WASHENFELDER,REBECCA A.; BUSSMANN, D. ANDREW; GRUBBS, ROBERT H.; J. Am.Chem. Soc. 122 (2000) 1, 58-71; Arnold and Mabel Beckman Lab. Chem.Synth., Calif. Inst. Technol., Pasadena, CA 91125, USA; EN)

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2000 alkylation, arylation, dealkylation, dearylation, C-acylation, olefination

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