complex natural products. However, in recent years it became apparent that these
olefinations are also suitable lactonization steps since they are compatible with a
variety of functional groups and tolerate most of the employed conditions. Based on
this state of knowledge, the intramolecular Wittig olefination reaction has been
successfully applied in the preparation of 2E unsaturated 12-membered macrolides.
In 1993, Bestmann et al. reported the synthesis of (+)-patulolide A 116 by this
procedure [74]. The key step in this synthesis was the reaction of keteneylide
triphenyl phosphorane 113 and hydroxy aldehyde 112 followed by subsequent
intramolecular Wittig olefination leading to ring-closure product 115 (Scheme 29).
Scheme 28 Intramolecular Yamamoto vinylogous aldol reaction as a key step in the synthesis of
(+)-peloruside A, 111
Scheme 29 Intramolecular Wittig reaction using keteneylidene triphenyl phosphorane, 113
Synthesis of 12- to 16-Membered-Ring Lactones
393
olefinations are also suitable lactonization steps since they are compatible with a
variety of functional groups and tolerate most of the employed conditions. Based on
this state of knowledge, the intramolecular Wittig olefination reaction has been
successfully applied in the preparation of 2E unsaturated 12-membered macrolides.
In 1993, Bestmann et al. reported the synthesis of (+)-patulolide A 116 by this
procedure [74]. The key step in this synthesis was the reaction of keteneylide
triphenyl phosphorane 113 and hydroxy aldehyde 112 followed by subsequent
intramolecular Wittig olefination leading to ring-closure product 115 (Scheme 29).
Scheme 28 Intramolecular Yamamoto vinylogous aldol reaction as a key step in the synthesis of
(+)-peloruside A, 111
Scheme 29 Intramolecular Wittig reaction using keteneylidene triphenyl phosphorane, 113
Synthesis of 12- to 16-Membered-Ring Lactones
393