TY - JOUR
T1 - Asymmetric formal synthesis of (-)-pancracine via catalytic enantioselective C-H amination process
AU - Anada, Masahiro
AU - Tanaka, Masahiko
AU - Shimada, Naoyuki
AU - Nambu, Hisanori
AU - Yamawaki, Minoru
AU - Hashimoto, Shunichi
N1 - Funding Information:
This research was supported, in part, by a Grant-in-Aid for Scientific Research on Priority Areas ‘Advanced Molecular Transformations of Carbon Resources’ from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We thank S. Oka, M. Kiuchi, and T. Hirose of the Center for Instrumental Analysis at Hokkaido University for mass measurements and elemental analysis.
PY - 2009/4/18
Y1 - 2009/4/18
N2 - The reaction of silyl enol ethers derived from cyclohexanone with [(4-nitrophenylsulfonyl)imino]phenyliodinane (pNsN{double bond, long}IPh) 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 (-)-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.
AB - The reaction of silyl enol ethers derived from cyclohexanone with [(4-nitrophenylsulfonyl)imino]phenyliodinane (pNsN{double bond, long}IPh) 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 (-)-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.
KW - (-)-Pancracine
KW - Amaryllidaceae alkaloids
KW - C-H amination
KW - Chiral dirhodium(II) catalyst
UR - http://www.scopus.com/inward/record.url?scp=62049083460&partnerID=8YFLogxK
U2 - 10.1016/j.tet.2008.10.091
DO - 10.1016/j.tet.2008.10.091
M3 - 学術論文
AN - SCOPUS:62049083460
SN - 0040-4020
VL - 65
SP - 3069
EP - 3077
JO - Tetrahedron
JF - Tetrahedron
IS - 16
ER -