First Stereoselective Total Synthesis of Ciryneol C

The acetylene derivative Ciryneol C was isolated from the roots of C. japonicum. The asymmetric total synthesis of Ciryneol C was achieved in seven steps, with Horner–Wittig olefination, regioselective epoxide opening, and Cadiot–Chodkiewicz coupling reactions being the key steps.

Methyl 3-(5-(prop-1-yn-1-yl)thiophen-2-yl)propanoate: A Rare Acetylene Derivative from Artemisia absinthium Root Essential Oil

Methyl 3-(5-(prop-1-yn-1-yl)thiophen-2-yl)propanoate (1), biosynthetically and structurally related to dehydromatricaria ester, was isolated from the root essential oil of Artemisia absinthium L. (0.7% of the total oil). This is the second record of this compound and the very first one regarding it as an essential-oil constituent. In this paper, we give details regarding its isolation, structural elucidation and gas chromatographic properties (RI on DB-5 MS column: 1694). The NMR-based identification of the compound was corroborated by simulation of its 1H- and 13C-NMR spectra using a GIAO method (DFT level of theory). A tentative biosynthetic pathway, possibly leading to this compound, is also proposed.

Spectral properties and photophysics of arylacetylenes in thin films

We report the photobehaviour of a series of eight structurally related arylacetylene derivatives, in solution as well as in pristine and PC61BM blended thin-_lms. The formation of both H- and J-aggregates in the solid state have been demonstrated, and, interestingly, an energy transfer from H-aggregates or/and from residual "unstacked" molecules to J-aggregates has been found, the latter being the only emitting species. The fuorescence quenching by PC61BM at di_erent loadings has been studied in blend films, and it has been found particularly effcient in the case of a symmetrical peripheral substitution of the acetylene derivative core. Preliminary time-resolved measurements in emission (ns resolution) and in absorption (fs resolution) con_rmed the H⟶J energy transfer and underlined the presence of delayed fuorescence from Jaggregates, formed by energy transfer from the long-lived first excited singlet state of H-aggregates. In all cases, a homogeneous surface morphology of thin films.

Reactions of 1,3-dipolar aldazines and ketazines with the dipolarophile dimethyl acetylenedicarboxylate

The prepared aldazines (aldehyde azines) and ketazines (ketone azines) were allowed to react with 2 mol of the acetylene derivative. The first products formed were pentalene azine derivatives, which in some cases underwent skeletal rearrangment into acyclic tetraene azines. The latter underwent, in the case of some aldazine products, further skeletal rearrangment into N-allyl pyrazoles. The occurence of these rearrangments is dependant on the nature of the aldehydes or ketones used.Key words: dimethyl acetylenedicarboxylate (DMAD), aldazines, ketazines, N-allyl pyrazoles.