An iridium-catalyzed allylation/esterification cascade reaction of spirotetramic acid derivatives has been developed, affording chiral 3-allylic spirotetramic acid ester derivatives with excellent enantioselectivity (94-99% ee) in moderate to high yields (43-97%). Meanwhile, a sequential iridium- and cinchona alkaloid-catalyzed double allylations reaction was established, yielding chiral 3-allylic spirotetramic acid derivatives bearing two stereogenic centers with excellent enantioselectivity (99% ee) and moderate to high diastereoselectivity (4:1 to >20:1 dr) in moderate to good yields (43-70%). The target compound 4d exhibited promising insecticidal activity against Aphis craccivora, with the activity of (S)-4d (LC50 = 0.094 g·L-1) being significantly higher than that of (R)-4d (LC50 = 0.174 g·L-1) and its racemate (LC50 = 0.178 g·L-1).
Tao et al. (Wed,) studied this question.