The ¹H NMR spectra of exo‐ and endo‐3‐thiatricylo[4.2.1.0^2,5]non‐7‐ene 3,3‐dioxide. The shielding effect of the sulfone group

Abstract

The proton spectra of exo-and end0-3-thiatricyclo[4.2.1.0~'~]non-7-ene 3,3-dioxide have been analysed and completely assigned. Considerations of coupling constants indicate that the thietane ring is nonplanar and that the norbornene residue is significantly distorted from the geometry of norbornene itself. The sulfone group induces significant changes in the shielding of the proximate olefinic proton in the endo isomer and the bridge protons in the ex0 isomer. These shifts appear to be the result of the electrostatic effects and effects associated with the diagmagnetic anisotropy of the sulfone group.

Metal-Catalyzed Addition Polymers for 157 nm Resist Applications. Synthesis and Polymerization of Partially Fluorinated, Ester-Functionalized Tricyclo[4.2.1.02,5]non-7-enes

“…The spectra were compared with the available published spectral data 10e,16,31 for other tricyclo[4.2.1.0 2,5 ]non-7-ene compounds. The exo configuration of the cyclobutane ring fusion was established by the W-coupling between H(9 syn ) and H(2) and H(5) ( 4 J = 1.7 Hz), that is similar to the reported values for exo -3-thiatricyclo[4.2.1.0 2,5 ]non-7-ene-3,3-dioxide …”

“…The exo configuration of the cyclobutane ring fusion was established by the W-coupling between H(9 syn ) and H(2) and H(5) ( 4 J ) 1.7 Hz), that is similar to the reported values for exo-3-thiatricyclo[4.2.1.0 2,5 ]non-7-ene-3,3dioxide. 32 The bridgehead protons H(1) and H(6) each appear as distinct unresolved multiplets with the H(1) proton appearing about 0.08 ppm downfield from H(6). The ∆δ for H(1)-H(6) is diagnostic of syn and anti due to deshielding by the nearby substituents on C(3).…”