Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• the developed strategy ended up failing in more complex and sterically demanding systems. Keywords: B-seco limonoids; biology oriented synthesis; Ireland–Claisen rearrangement; natural products; tetranortriterpenoids; Introduction B-seco limonoids are a family of more than 100 highly oxygenated

• modulators [26]. B-seco limonoids constitute exceptionally challenging synthesis targets, as the characteristic structural features are a compact, highly oxygenated as well as richly decorated framework and stereochemically dense functionalization. In all B-seco limonoids an A ring is linked by a C–C bond to

• substitution of C14 with a bulky group (1,2-allylic strain) the ring inversion barrier of the cyclohexene conformations might be increased, resulting in higher de values. These model studies suggested that an Ireland–Claisen rearrangement is a feasible strategy to construct the C9–C10 bond in B-seco limonoids