✦ LIBER ✦
Diastereo- and Enantioselective Synthesis of Lignan Building Blocks by Tandem Michael Addition/Electrophilic Substitution of Lithiated α-Amino Nitriles to Furan-2(5H)-one
✍ Scribed by Enders, Dieter ;Kirchhoff, Jochen ;Lausberg, Vivien
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 728 KB
- Volume
- 1996
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
Starting from chiral α‐amino nitriles (S,S,R/S)‐3, we prepared β‐aroyl‐γ‐butyrolactones (S)‐5 as well as 2,3‐disubstituted γ ‐butyrolactones (S,S)‐ or (R,S,R)‐6 in high yields and with high enantiomeric excesses by conjugate addition to butenolide, followed by protonation, α‐alkylation or α‐aldol addition, respectively. The introduction of one up to three stereogenic centers opens a flexible and highly efficient diastereo‐ and enantioselective route to 2,3‐dibenzylated γ‐butyrolactones 6, which proved to be important lignan building blocks.