innovative approach to direct (in terms of chemoselectivity) and discipline (in terms
of regiochemistry of dienolate formation and attack) the course of the vinylogous
aldol reaction is undoubtedly a prime achievement in the aldol field. The observed
regioselectivity is in fact unattainable under standard conditions, and both the
architecture and function of aluminium tris(2,6-diphenoxide) (ATPH) in this reaction are reminiscent of enzymes active centers.
7.2 16-Membered Macrocyclic Lactones
7.2.1 (+)-Peloruside A
The intramolecular Yamamoto vinylogous aldol reaction (lithium 2,2,6,6tetramethyl-piperidine
(LTMP)
(two
equivalent),
aluminum
tris
(2,6-diphenylphenoxide) (ATPH) (2.2 equivalent), toluene/THF, –48
C) of 109
proceeded in high yield (84 %) and good levels of diastereoselectivity (dr ¼ 6:1) to
deliver 16-membered peloruside precursor 110 [73] (Scheme 28).
8 Wittig and HWE Transformations in Macrolactone
Formation
8.1 12-Membered Macrocyclic Lactones
8.1.1 (+)-Patulolide A
The Wittig and Wittig-type reactions belong to the most reliable and widely
employed transformations for joining large segments during total syntheses of
Scheme 27 Application of the intramolecular Yamamoto vinylogous aldol reaction to the synthesis of macrolides
392
M. Cordes and M. Kalesse
of regiochemistry of dienolate formation and attack) the course of the vinylogous
aldol reaction is undoubtedly a prime achievement in the aldol field. The observed
regioselectivity is in fact unattainable under standard conditions, and both the
architecture and function of aluminium tris(2,6-diphenoxide) (ATPH) in this reaction are reminiscent of enzymes active centers.
7.2 16-Membered Macrocyclic Lactones
7.2.1 (+)-Peloruside A
The intramolecular Yamamoto vinylogous aldol reaction (lithium 2,2,6,6tetramethyl-piperidine
(LTMP)
(two
equivalent),
aluminum
tris
(2,6-diphenylphenoxide) (ATPH) (2.2 equivalent), toluene/THF, –48
C) of 109
proceeded in high yield (84 %) and good levels of diastereoselectivity (dr ¼ 6:1) to
deliver 16-membered peloruside precursor 110 [73] (Scheme 28).
8 Wittig and HWE Transformations in Macrolactone
Formation
8.1 12-Membered Macrocyclic Lactones
8.1.1 (+)-Patulolide A
The Wittig and Wittig-type reactions belong to the most reliable and widely
employed transformations for joining large segments during total syntheses of
Scheme 27 Application of the intramolecular Yamamoto vinylogous aldol reaction to the synthesis of macrolides
392
M. Cordes and M. Kalesse