1451152-72-9Relevant academic research and scientific papers
Doing it twice: Asymmetric deprotonation/alkylation of weiss diketone derivatives as key steps in the functionalization of bicyclo[3.3.0]octanes
Lutz, Vanessa,Park, Natja,Rothe, Christian,Krueger, Claudia,Baro, Angelika,Laschat, Sabine
, p. 761 - 771 (2013/03/28)
The silyl-protected allylhydropentalenone derivative 9, derived from the Weiss diketone, was functionalized by enantioselective deprotonation in the presence of lithium bis(1-phenylethyl)amide/LiCl as the chiral base, which was generated in situ from bis(1-phenylethyl)ammonium chloride [(R,R)- or (S,S)-14] and BuLi, and trapping of the resulting enolate with alkyl halide electrophiles to give pseudo-C2 or -Cs-symmetrical bicyclo[3.3.0] octanones 10 and 11. The influence of the chiral base and electrophiles on the regioselectivity and double stereodifferentiation was investigated. Taking the double stereocontrol into account, a matched selectivity for the pseudo-C 2 pair (1R,4R)-10/(1S,4R)-10 and a mismatched selectivity for the pseudo-Cs pair (1S,6R)-11/(1R,6R)-11 were observed in the presence of (R,R)-14. The use of (S,S)-14, however, produced a mismatched selectivity for (1R,4R)-10/(1S,4R)-10 and a matched selectivity for (1S,6R)-11/(1R,6R)-11 with complementary diastereoselectivity depending on the electrophile. Furthermore, the hydropentalenone derivative 10a provided an alternative route to the bicyclo[3.3.0]octene core of the macrocyclic tetramic acid lactam, cylindramide (5). Pseudo-C2-symmetrical bicyclo[3.3.0]octanones 2 have been prepared from enantiopure α-substituted derivatives 1 of the Weiss diketone. The symmetrical bicyclo[3.3.0]octanones 2 were then converted into the hydropentalene core of macrocyclic polyketide tetramic acid lactams such as cylindramide. Copyright
