Negative photochromism of a blue cyanine dye.

We found a novel blue cyanine dye that exhibits negative photochromism. Upon photoexcitation of the dye solution, the blue colour visibly disappeared, and after several hours the absorbance of the solution recovered completely, indicating that the dye has high stability.

Enantiocontrolled synthesis of jasmonates via tandem retro-Diels-Alder-ene reaction activated by a silyl substituent.

[reaction: see text] An enantiocontrolled synthesis of (-)-methyl 6-epi-cucurbate and (+)-methyl jasmonate was established from a chiral tricyclic lactone via a new type of tandem retro-Diels-Alder-ene reaction activated by a trimethysilyl substituent as the key step.