期刊
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
卷 2012, 期 4, 页码 699-707出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/ejoc.201101336
关键词
Synthetic methods; Asymmetric catalysis; C-C coupling; Amino alcohols; Carbene ligands
资金
- Engineering and Physical Research Council (EPSRC)
- Engineering and Physical Sciences Research Council [EP/F033478/1] Funding Source: researchfish
- EPSRC [EP/F033478/1] Funding Source: UKRI
A one-pot reaction of Boc-protected amino alcohols and 2-sulfobenzoic anhydride followed by the addition of a wide variety of primary amines has allowed rapid access to diverse libraries of amidosulfonates 1,2-C6H4(SO3)(COCHR1CH2NH2+R2) (R1 = Bn, iPr, Ph; R2 = aryl, CHMePh, 1-adamantyl), of which two examples have been characterised by X-ray crystallography. These reactions proceed by SN2 opening of unisolated oxazoline intermediates. The amidosulfonates have been converted to imidazolinium sulfonate zwitterions (N-heterocyclic carbene precursors) in a two-step process, which involved reduction with BH3.SMe2 and cyclisation with HC(OEt)3. Two examples (R1 = Bn, R2 = 2,6-iPrC6H3 and R1 = iPr, R2 = 3,5-Me2C6H3) have been crystallographically characterised, the latter as a PF6 salt. The imidazolinium sulfonate zwitterions (1 mol-%) catalysed additions of RMgBr (R = alkyl) to (E)-ArC(R)=CHCH2Br (R = H, Me). Additions to cinnamyl bromides showed high ? (SN2') selectivity (up to 18.4:1) and provided significantly enantiomerically enriched products (up to 82?% ee).
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