On the structural features of the chiral organometallic Lewis-acid catalyst “(dibornacyclopentadienyl)zirconiumtrichloride”
摘要:
2-Bornenyllithium (3) was prepared from camphor by a variant of the Shapiro reaction and then reacted with 0.5 molar equivalents of ethylformate to give the dibornenylcarbinol 4. Subsequent acid-catalyzed cyclization of 4 yielded ''dibornacyclopentadiene'' as a mixture of two diastereoisomers; their deprotonation with n-butyllithium produced a single ''dibornacyclopentadienyllithium'' reagent (6). Reaction of 6 with MCl4 (M = Zr, Hf, Ti) gave the chiral organometallic Lewis-acids ''(diborna-CP)MCl3''. ''(+)-(Dibornacyclopentadienyl)zirconiumtrichloride'' (7a) was characterized by X-ray diffraction. The molecular structure of 7a provides a basis for discussing the stereochemical characteristics of the enantioselective arene hydroxyalkylation process catalyzed by the optically active organometallic Lewis-acid ''(dibornacyclopentadienyl)zirconiumtrichloride''.
On the structural features of the chiral organometallic Lewis-acid catalyst “(dibornacyclopentadienyl)zirconiumtrichloride”
摘要:
2-Bornenyllithium (3) was prepared from camphor by a variant of the Shapiro reaction and then reacted with 0.5 molar equivalents of ethylformate to give the dibornenylcarbinol 4. Subsequent acid-catalyzed cyclization of 4 yielded ''dibornacyclopentadiene'' as a mixture of two diastereoisomers; their deprotonation with n-butyllithium produced a single ''dibornacyclopentadienyllithium'' reagent (6). Reaction of 6 with MCl4 (M = Zr, Hf, Ti) gave the chiral organometallic Lewis-acids ''(diborna-CP)MCl3''. ''(+)-(Dibornacyclopentadienyl)zirconiumtrichloride'' (7a) was characterized by X-ray diffraction. The molecular structure of 7a provides a basis for discussing the stereochemical characteristics of the enantioselective arene hydroxyalkylation process catalyzed by the optically active organometallic Lewis-acid ''(dibornacyclopentadienyl)zirconiumtrichloride''.
A convenient synthesis of (–)-N-styryl-N-[2-(1,7,7-trimethylbicyclo[2.2.1]hept-2-enyl)ethyl]formamide (2) was developed starting from natural (+)-camphor (3) via (–)-2-(bornen-2-yl)ethanol (6). Cyclization of the N-formylenamine 2 with the aid of 9-borabicyclo[3.3.1]non-9-yl triflate yielded a methanobridged octahydro-1H-benzo[d]azepine derivative.
从天然(+)开始开发了一种方便的合成(-)- N-苯乙烯基-N- [2-(1,7,7-三甲基双环[2.2.1]庚-2-烯基)乙基]甲酰胺(2)的方法-(2-3)经由(–)-2-(冰片-2-基)乙醇(6)合成-樟脑。借助9-硼杂环[3.3.1]非-9-基三氟甲磺酸酯对N-甲酰亚胺2进行环化,生成甲亚甲基桥连的八氢-1 H-苯并[ d ] ze庚因衍生物。
On the structural features of the chiral organometallic Lewis-acid catalyst “(dibornacyclopentadienyl)zirconiumtrichloride”
作者:Gerhard Erker、Jutta Schamberger、Adolphus A.H. van der Zeijden、Stefan Dehnicke、Carl Krüger、Richard Goddard、Matthias Nolte
DOI:10.1016/0022-328x(93)86061-l
日期:1993.10
2-Bornenyllithium (3) was prepared from camphor by a variant of the Shapiro reaction and then reacted with 0.5 molar equivalents of ethylformate to give the dibornenylcarbinol 4. Subsequent acid-catalyzed cyclization of 4 yielded ''dibornacyclopentadiene'' as a mixture of two diastereoisomers; their deprotonation with n-butyllithium produced a single ''dibornacyclopentadienyllithium'' reagent (6). Reaction of 6 with MCl4 (M = Zr, Hf, Ti) gave the chiral organometallic Lewis-acids ''(diborna-CP)MCl3''. ''(+)-(Dibornacyclopentadienyl)zirconiumtrichloride'' (7a) was characterized by X-ray diffraction. The molecular structure of 7a provides a basis for discussing the stereochemical characteristics of the enantioselective arene hydroxyalkylation process catalyzed by the optically active organometallic Lewis-acid ''(dibornacyclopentadienyl)zirconiumtrichloride''.