کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5227135 | 1383597 | 2009 | 9 صفحه PDF | دانلود رایگان |
The reaction of silyl enol ethers derived from cyclohexanone with [(4-nitrophenylsulfonyl)imino]phenyliodinane (pNsNIPh) catalyzed by dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate], Rh2(S-TCPTTL)4, provides, after desilylation, N-pNs-protected (S)-β-aminocyclohexanone in up to 72% ee. This represents the first example of the insertion of nitrene species into an allylic C-H bond of silyl enol ethers. Using this process, a new catalytic asymmetric route to an advanced intermediate in Overman's synthesis of the montanine-type Amaryllidaceae alkaloid (â)-pancracine has been developed. The key steps involve (a) a one-pot Rh2(R-TCPTTL)4-catalyzed sequential 1,4-hydrosilylation/enantioselective C-H amination of 2-cyclohexen-1-one, (b) N-alkylation and subsequent intramolecular Mukaiyama aldol reaction/dehydration, and (c) a regio- and stereocontrolled reductive deoxygenation of bicyclic enone 27 with migration of the double bond to create the C1/C11a double bond and the stereogenic center at C11 of 3-arylhexahydroindole 31.
Journal: Tetrahedron - Volume 65, Issue 16, 18 April 2009, Pages 3069-3077