Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, UK.
Org Lett. 2011 May 20;13(10):2606-9. doi: 10.1021/ol200717n. Epub 2011 Apr 13.
Aminohydroxylation of tert-butyl sorbate [tert-butyl (E,E)-hexa-2,4-dienoate] using enantiopure lithium (R)-N-benzyl-N-(α-methylbenzyl)amide and (-)-camphorsulfonyloxaziridine gives tert-butyl (R,R,R,E)-2-hydroxy-3-[N-benzyl-N-(α-methylbenzyl)amino]hex-4-enoate in >99:1 dr. Subsequent dihydroxylation under Upjohn conditions (OsO(4)/NMO) gives tert-butyl (2R,3R,4S,5S,αR)-2,4,5-trihydroxy-3-[N-benzyl-N-(α-methylbenzyl)amino]hexanoate (in 95:5 dr) while dihydroxylation under Donohoe conditions (OsO(4)/TMEDA) proceeds with antipodal diastereofacial selectivity to give the (R,R,R,R,R)-diastereoisomer (in 95:5 dr). The amino triols resulting from these dihydroxylation reactions are useful for further elaboration, as demonstrated by the asymmetric synthesis of 3,6-dideoxy-3-amino-L-talose.
叔丁基琥珀酸酯[叔丁基（E，E）-己-2,4-二烯酸酯]的氨羟化作用，使用手性纯的锂（R）-N-苄基-N-（α-甲基苄基）酰胺和（-）樟脑磺酰基恶唑啉，得到>99:1 dr 的叔丁基（R，R，R，E）-2-羟基-3-[N-苄基-N-（α-甲基苄基）氨基]己-4-烯酸酯。随后在 Upjohn 条件（OsO(4)/NMO）下进行二羟基化反应，得到叔丁基（2R，3R，4S，5S，αR）-2,4,5-三羟基-3-[N-苄基-N-（α-甲基苄基）氨基]己酸酯（95:5 dr），而在 Donohoe 条件（OsO(4)/TMEDA）下进行二羟基化反应，则具有对映面选择性，得到（R，R，R，R，R）-非对映异构体（95:5 dr）。这些二羟基化反应得到的氨基三醇可用于进一步的修饰，如通过不对称合成 3,6-二脱氧-3-氨基-L-塔洛糖得到证明。
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