133124-32-0Relevant academic research and scientific papers
Functionalized Carbocycles by Tandem Dealkoxycarbonylation-Michael Addition Reactions
Bunce, Richard A.,Dowdy, Eric D.,Jones, Paul B.,Holt, Elizabeth M.
, p. 7143 - 7148 (1993)
A tandem dealkoxycarbonylation-Michael addition reaction has been developed as a synthetic route to highly functionalized carbocycles.Methyl esters, activated toward decarboxylation by an electron-withdrawing group at C-2 and tethered by a three- or four-carbon chain to an acrylate Michael acceptor, have been prepared and used as the cyclization substrates.Treatment of these compounds with LiCl in HMPA at 120 deg C for 4 h results in selective SN2 dealkylation of the methyl esters, decarboxylation, and cyclization of the intermediate anions by a Michael addition to the pendant acrylate moiety.This affords 45-90percent of the cyclopentane- and cyclohexaneacetic esters substituted at C-2 by an electron-withdrawing group.Moderate to excellent selectivity (3:1 - 99:1) in favor of the product having the electron-withdrawing group trans to the acetic ester side chain is observed.The reaction works best for the preparation of five-membered rings, and cyclizations proceed most cleanly from substrates which cyclize through a tertiary carbanion.Synthetic and mechanistic details as well as optimization studies and product structure proofs are presented.
A second generation synthesis of roseophilin and chromophore analogues
Furstner,Gastner,Weintritt
, p. 2361 - 2366 (1999)
A concise, flexible, and high-yielding synthesis of the macrocyclic compound 4 is outlined which served as a key intermediate in a previous total synthesis of the antitumor active alkaloid roseophilin 1. The key steps of this approach consist of a Pd(0)-catalyzed reaction of vinyloxirane 6 with sulfone 7 and in a subsequent ring closing metathesis (RCM) reaction for the formation of the 13-membered ring catalyzed by the ruthenium carbene Cl2(PCy3)2Ru=CHCH=CPh2 introduced by Grubbs. Moreover, nitrile ylide cycloaddition reactions are used for the preparation of roseophilin side chain mimics. Finally, the synthesis of various chromophore analogues of 1 is reported, including deschlorodesmethoxyroseophilin 12 which is the most elaborate derivative of this complex target reported so far.
