Short synthesis, -cylindricine

Shibasaki M, Shibuguchi T, Mihara H, Kuramochi A, Sakuraba S, Ohshrma T (2006) Short Synthesis of (-l-)-Cylindricine C by Using a Catalytic Asymmetric Michael Reaction with a Two-Center Organocatalyst. Angew Chem Int Ed 45 4635... 

Mihara H, Shibuguchi T, Kuramochi A, Ohshima T, Shibasaki M (2007) Short Synthesis of (-t)-Cylindricine C and Formal Total Synthesis of (-)-Lepadiformine. Heterocycles 72 421... 

Shibuguchi, M., Mihara, H., Kuramochi, A., Sakuraba, S., Ohshima, T., Shibasaki, M. (2006). Short synthesis of (-l-)-cylindricine C by using a catalytic asymmetric Michael reaction with a two-center organocatalyst. Angewandte Chemie International Edition, 45, 4635-4637. 

Short Syntheses of (+)-Cylindricine and Formal Synthesis of (-)-Lepadiformine... 

The Shibasaki group also demonstrated the potential of their Ca-symmetric diammonium salt catalyst 135 for the syntheses of the alkaloids (+)-cylindricine C (138) and (—)-lepadiformine (139) [22c,68,69], By applying a PT-catalyzed addition of Schiff base 140 to Michael acceptor 141, the key intermediate 142 was obtained in good yield and with good enantiomeric excess. Compound 142 could then be used to obtain selectively either the cylindricine C precursor 143 or the lepadiformine synthon 144 in a very efficient tandem cyclization reaction by choosing the optimum reagents. The impressively short total synthesis of (+)-cylindricine C (138) could be achieved in only two additional steps, whereas the synthesis of the tricyclic intermediate 144 represents a formal total synthesis of (—)-lepadiformine (139) (Scheme 28). 

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