Abstract
Diastereoselective carbon-carbon bond formation is accomplished using activated imines with organocuprates-BF3·OEt2 complexes or allylic organometallic compounds such as allyl-9-BBN and allyltributylstannane-TiCl4. Very high 1, 2- and 1, 3-asymmetric induction is achieved in the reaction of allyl-9-BBN, allylmagnesium chloride and allylaluminum ate complexes with certain chiral imines. Iminium ion intermediates generated from α-alkoxycarbamates are detected by NMR at low temperatures. Significantly high diastereoselectivities are observed in the reactions of iminium ions with organoleads, allylic stannanes and organocuprate-BF3 reagents. It is proposed that ZnCl2·OEt2 works as a radical initiator as well as a chelating agent in the reaction of the ZnCl2 mediated allylation of α-bromoglycine derivatives with allylic stannanes. Transition metal catalyzed C-C bond formation takes place successively in the reaction of activated imines with activated nucleophiles such as malononitrile and α-alkoxy malononitrile. Lithium N -benzyltrimethylsilylamide (LSA) regioselectively adds to α, β-unsaturated esters in a 1, 4-manner. Higher order cyano cuprate type analogues of LSA react regioseletively with α, β, γ, δ-unsaturated esters in a 1, 4-manner to give the corresponding β-amino esters. This cuprate amide reagent is applied to the highly stereoselective synthesis of β-lactam frameworks. Asymmetric carbocyclization is achieved via the tandem conjugate addition of metal amides to certain dienoates.
Original language | English |
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Pages (from-to) | 1005-1012 |
Number of pages | 8 |
Journal | Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry |
Volume | 51 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1993 |
Keywords
- Activated imines
- Allylic organometallic compounds
- Amide cuprates
- Asymmetric conjugate addition
- Carbapenem antibiotics
- Iminium ion intermediates
- Metal amides
- Nitrogen containing compounds
- Transition metal catalyzed C-C bond formation
- β-Lactam
ASJC Scopus subject areas
- Organic Chemistry