Regio- and Stereoselectivity of the SiO2-Catalyzed Reaction of Thiocamphor (=1,7,7-Trimethylbicyclo[2.2.1]heptane-2-thione) with Optically Active Monosubstituted Oxiranes
作者:Changchun Fu、Anthony Linden、Heinz Heimgartner
DOI:10.1002/hlca.200390182
日期:2003.6
The reactions of the enolizable thioketone (1R,4R)-thiocamphor (=(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptane-2-thione; 1) with (S)-2-methyloxirane (2) in the presence of a Lewis acid such as SnCl4 or SiO2 in anhydrous CH2Cl2 led to two diastereoisomeric spirocyclic 1,3-oxathiolanes 3 and 4 with the Me group at C(5′), as well as the isomeric β-hydroxy thioether 5 (Scheme 2). The analogous reactions
可烯化的硫酮(1 R,4 R)-硫樟基(=(1 R,4 R)-1,7,7-三甲基双环[2.2.1]庚烷-2-硫酮; 1)与(S)-的反应2-甲基环氧乙烷(2在存在下)一个路易斯酸如的SnCl 4或SiO 2在无水CH 2氯2导致了两个非对映异构螺环-1,3-氧硫杂环戊烷3和4与Me基团在C(5'),以及异构体β-羟基硫醚5(方案2)。的类似反应1用(RS) - ,(- [R )-和(小号)-2-苯基环氧乙烷(7),得到两种异构螺环-1,3-氧硫杂环戊烷8和9与pH为C(4'),附加的异构体13轴承C(5')上的Ph基团和三个异构的β-羟基硫醚10、11和12(方案4)。在HCl存在下,β -羟基硫醚5,10,11,和12异构化成相应的1,3-氧硫杂环戊烷3和4(方案3),和分别如图8、9和13所示(方案5)。在类似条件下,的差向异构化3,8,和9发生,得到相应的非对映体4,14,和15,分