Chiroptical properties, structure, and absolute configuration of heterosubstituted 2(5H)-furanones

Abstract

Chiroptical properties of a series of 3 and/or 4‐heterosubstituted 2(5H)‐furanones were investigated with respect to correlation with absolute configuration. The n − π* and π − π* Cotton effects have been assigned on the basis of comparison with the UV spectra in solvents of varying polarity. It is demonstrated that the n − π* transition in 4‐amino substituted 2(5H)‐furanones appears at shorter wavelength with respect to the π − π* transition. With the exception of 4‐pyrrolidino and 4‐benzylamino substituted 2(5H)‐furanones, other heterosubstituted 2(5H)‐furanones follow the butenolide configurational rule (Gawronski et al. J. Org. Chem. 61:1513–1515, 1996). Absolute configuration of 2(5H)‐furanone derivatives can also be assigned according to the sign of the Cotton effect (of unknown origin) at 200–230 nm. The structure of four representative sulfur and nitrogen substituted 2(5H)‐furanones has been analyzed by X‐ray diffraction. The results indicate planarity of the furanone ring and extended conjugation in 4‐amino substituted 2(5H)‐furanones. Chirality 9:537–544, 1997. © 1997 Wiley‐Liss, Inc.

UV-induced unimolecular photochemistry of 2(5H)-furanone and 2(5H)-thiophenone isolated in low temperature inert matrices

“…This observation is in agreement with the UV absorption spectra of the two compounds. The lowest energy UVabsorption for thiophenone was experimentally observed at 263 nm (in ethanol) [37,38], while the lowest energy absorption for furanone varies in different solvents [39][40][41] from 220 nm (in ethanol) [41] to 201 nm (in methanol) [42]. The photoinduced changes in infrared spectrum of matrix-isolated furanone are presented in Fig.…”

Molecular structure and vibrational spectra of 2(5H)-furanone and 2(5H)-thiophenone isolated in low temperature inert matrix

“…Furanone and thiophenone possess an sp 3 carbon atom (at position 5, see Scheme 1) that, in the presence of unequal substituents (at positions 9 and 10), affords chirality. Then, furanone and thiophenone are used in stereoselective synthesis [15,16] to produce chiral compounds and to determine the influences and relative configurations of stereogenic centres [17,18].…”

A New 2,3-Dimethyl Butenolide from the Brittle Star Ophiomastix mixta

“…This pattern of Cotton effect was similar to that of the g-methoxy-galkyl-disubstituted butenolides (ϩ0.37, 205 nm, 4; ϩ14.0, 204 nm, 6). 10,27) The red-shift in the CD spectrum of 1, compared to that of 4, might be due to 2,3-dimethyl substitution. 28) In contrast, 1 showed opposite Cotton effect to 5 (Ϫ0.58, 206 nm, 5), which has opposite stereochemistry to 4 (Fig.…”