5.2 14-Membered Macrocyclic Lactones
5.2.1 (–)-Callipeltoside A
The antitumor natural product (–)-callipeltoside A 88 has been a popular aim for
total synthesis due to its complex architecture and promising bioactivity. The most
impressive contribution to this target, concerning macrolactonization strategy, was
probably made by Hoye and coworkers to accomplish both the macrolactonization
and the transannular hemiketal formation as a one-pot protocol without the need of
protecting groups [62] (Scheme 21).
5.2.2 Norzoanthamine
A very recent example of β-keto ester thermolysis has been shown during the
synthesis of the carbocyclic core of norzoanthamine (Scheme 22). Macrocyclic
lactone 90 was then further elaborated to 91 using a transannular Michael reaction
cascade [64].
Scheme 21 Remarkable chemoselectivity in a tandem macrolactonization–hemiketalization
reaction
388
M. Cordes and M. Kalesse
5.2.1 (–)-Callipeltoside A
The antitumor natural product (–)-callipeltoside A 88 has been a popular aim for
total synthesis due to its complex architecture and promising bioactivity. The most
impressive contribution to this target, concerning macrolactonization strategy, was
probably made by Hoye and coworkers to accomplish both the macrolactonization
and the transannular hemiketal formation as a one-pot protocol without the need of
protecting groups [62] (Scheme 21).
5.2.2 Norzoanthamine
A very recent example of β-keto ester thermolysis has been shown during the
synthesis of the carbocyclic core of norzoanthamine (Scheme 22). Macrocyclic
lactone 90 was then further elaborated to 91 using a transannular Michael reaction
cascade [64].
Scheme 21 Remarkable chemoselectivity in a tandem macrolactonization–hemiketalization
reaction
388
M. Cordes and M. Kalesse