Premium
Carbon‐13 chemical shifts of 3‐substituted thietanes, thietane 1‐oxides and thietane 1,1‐dioxides
Author(s) -
Dittmer Donald C.,
Patwardhan Bhalchandra H.,
Bartholomew John T.
Publication year - 1982
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270180207
Subject(s) - sulfone , substituent , chemistry , chemical shift , sulfoxide , medicinal chemistry , ring (chemistry) , sulfur , carbon fibers , methylene , sulfide , organic chemistry , materials science , composite number , composite material
Carbon‐13 chemical shifts of the α‐ and β‐carbon atoms for 12 thietane 1,1‐dixides, 9 thietane 1‐oxides and 7 thietanes with a variety of 3‐substituents [H, CH(CO 2 Et) 2 , SEt, Br, SPh, Ph, Cl, NMe 2 , OH, OSiMe 3 , OAc, OEt] are correlated according to the nature of the sulfur atom (Y=sulfone, sulfoxide, sulfide) and the nature of the 3‐substituent (X) by the equations δ α = a Y + b X and δ β = a X + b Y , where a and b are parameters characteristic of X and Y. One‐bond coupling constants [J(CH)] are reported for 21 compounds. The chemical shifts for the α‐ and the β‐carbon atoms of the sulfones show the ‘fore‐membered ring sulfone effect’ (α‐carbon unusually deshielded, β‐carbon unusually shielded), but the α‐carbon‐hydrogen coupling constants are similar to those of the sulfoxides and sulfides; the β‐carbon‐hydrogen coupling constants are sensitive to the nature of the substituent (X) but no special β‐effect is observed. Comparison of the chemical shifts of the α‐methylene carbon atoms of 3‐phenyl‐, 3‐(β‐naphthyl)‐ and 3‐(α‐thienyl)‐thietes with those of the coresponding sulfones also reveals the ‘four‐membered ring sulfone effect’ cis ‐ and trans ‐3‐Substituted thietane 1‐oxides may be distinguished by the greater downfield shift for the β‐carbon atom in the trans ‐isomer.