Stereocontrolled elaboration of quaternary carbon centers involving the asymmetric michael-type alkylation of chiral imines: an efficient enantioselective access to (+)-vincamine

Spirolactams as Conformationally Restricted Pseudopeptides: Synthesis and Conformational Analysis

“…Treatment of alcohol 13a with NBS or MsCl yielded bromide 14a or mesylate 15a , respectively. Intramolecular alkylation , with NaH of both 14a and 15a gave the expected spirolactam 1a . Similarly, spirolactam 1b was prepared from spirolactone 11 by reaction with d -Leu-O t Bu to give hydroxy amide 13b , which was converted to its mesylate 15b and cyclized with NaH in the presence of crown ether.…”

Phosphoric Acid Catalyzed Desymmetrization of Bicyclic Bislactones Bearing an All‐Carbon Stereogenic Center: Total Syntheses of (−)‐Rhazinilam and (−)‐Leucomidine B

“…reported the desymmetrization of prochiral 1 to the piperidinone derivative 6 by cyclocondensation of 1 with a stoichiometric amount of ( R )‐phenylglycinol 5. However, rapid and enantioselective synthesis of 2 a (R=Et) remained to be developed 6. In connection with our ongoing projects focused on the synthesis of indole alkaloids,7 we became interested in desymmetrizing Kuehne’s aldehyde and its subsequent application in natural product synthesis.…”

Recent progress in the chemistry of monoterpenoid indole alkaloids derived from secologanin

“…57 In an alternative approach to lactam 238 by Costa and d'Angelo et al Michael addition of imine 241 onto methyl acrylate provided the key intermediate 242 in 83% yield with 90% ee. 58 This ketone was readily transformed into lactone 243 via ozonolysis of the derived enol ether, and finally the lactone was converted into lactam 238 by a fairly conventional sequence (Scheme 36).…”