A short synthesis of neolignans with a dihydrobenzo[b]furan skeleton is described. The strategy is based on a ring-closing metathesis to produce benzo[f][1,2]oxasilepines which are condensed with aromatic aldehydes in a modified Sakurai-Hosomi reaction. Natural dihydrodehydrodiconiferyl alcohol (1) and 3-0-demethyldihydrodehydrodiconiferyl alcohol (2) have been prepared in this way.
A Diastereoselective Route to<i>trans</i>-2-Aryl-2,3-dihydrobenzofurans through Sequential Cross-Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the
Catalytic Asymmetric Synthesis of Trisubstituted Aziridines
作者:Li Huang、William D. Wulff
DOI:10.1021/ja203754p
日期:2011.6.15
is described which provides for the direct asymmetric catalytic synthesis of trisubstituted aziridines fromimines and diazo compounds. While unactivated imines were not reactive to α-diazo carbonyl compounds in which the diazo carbon was disubstituted, N-Boc imines react with both α-diazo esters and α-diazo-N-acyloxazolidinones to give trisubstituted aziridines with excellent diastereo- and enantioselectivities
β-Amino Esters from the Reductive Ring Opening of Aziridine-2-carboxylates
作者:Wenjun Zhao、Zhenjie Lu、William D. Wulff
DOI:10.1021/jo501694h
日期:2014.11.7
A general study is undertaken to examine the scope of the reductive ring opening of aziridine-2-carboxylates with samarium diiodide. The competitionbetween C–C and C–N bondcleavage is examined as a function of the nature of the N-substituent of the aziridine, the nature of the substituent in the 3-position of the aziridine, and whether the substituent in the 3-position is in a cis or trans relationship
An asymmetric synthesis of the analogue 4a of isoproterenol and of di-o-pyvaloylepinephrine 3 which provides bothenantiomers in optically pure state is reported. The key step of the method is the highly diastereo-selective reduction (using DIBAL or DIBAL/ZnCl2) of a β-ketosulfoxide 7 which leads, as desired, to the (S)- or the (R)-configuration at C(1) (Schemes 4 and 5).