Unravelling Photochemical Relationships Among Natural Products fromAplysia dactylomela.
Aplydactone (1) is a brominated ladderane sesquiterpenoid that was isolated from the sea hareAplysia dactylomelatogether with the chamigranes dactylone (2) and 10-epi-dactylone (3). Given the habitat ofA. dactylomela, it seems likely that1is formed from2through a photochemical [2 + 2] cycloaddition. Here, we disclose a concise synthesis of1,2, and3that was guided by excited state theory and relied on several highly stereoselective transformations. Our experiments and calculations confirm the photochemical origin of1and explain why it is formed as the sole isomer. Irradiation of3with long wavelength UV light resulted in a [2 + 2] cycloaddition that proceeded with opposite regioselectivity. On the basis of this finding, it seems likely that the resulting regioisomer, termed "8-epi-isoaplydactone", could also be found inA. dactylomela.
Department of Chemistry, Ludwig-Maximilians-Universität , 81377 Munich, Germany.
Bryan S
BS
Matsuura
Department of Chemistry, Ludwig-Maximilians-Universität , 81377 Munich, Germany.
Patrick
P
Kölle
Department of Chemistry, Ludwig-Maximilians-Universität , 81377 Munich, Germany.
Dirk
D
Trauner
Department of Chemistry, Ludwig-Maximilians-Universität , 81377 Munich, Germany.
Regina
R
de Vivie-Riedle
Department of Chemistry, Ludwig-Maximilians-Universität , 81377 Munich, Germany.
Robin
R
Meier