β Scribed by Dominick Mobilio; Barbara De Lange
No coin nor oath required. For personal study only.
Cyclohexenones I were allowed to react with allyltrimethylsilane and three allyltributylstannanes in the presence of titanium tetrachloride. Products 2 and 2 were formed in ratios ranging from 7:l to 26:l (2:3). Ratios resulting from the use of other Lewis acids -support 4 as an intermediate which accounts for the observed stereoselectivity. Stereocontrol of remote asytnnetric centers is an important goal in synthetic organic chemistry. Reported here are our results of 1,4-asymmetric induction on six-membered rings arising out of Lewis acid catalyzed addition of allyltrimethylsilane and three allyltributylstannanes to 6,6-disubstituted-cyclohexenones. Cyclohexenones 1 (R=Me or Et) were prepared from 2-ethylcyclohexanone or 2-methylcyclohexanone by a short sequence (Scheme 1). Alkylation with methyl bromoacetate by the method of Negishi' afforded the saturated ketones in 35-50% yield with about 5-10% of the 2,6-regioisomers being formed in both cases.2 These by-products were separated by flash chromatography.3
π SIMILAR VOLUMES
## Abstract magnified image Synthesis of alkyl/aryl [2β(1,2,4,5βtetrahydroβ3βsulfanylene/selenylene naphtha[1,8β__f__,__g__][1,5,3]diazaphosphocinβ3βyl) methyl amino acid esters] (**6**, **7**, **8**, **9**, **10**, **11**, **12**, **13**, **14**, **15**) was accomplished in three steps. 1, 8βdiam