Aromaticities of Five Membered Heterocycles through Dimethyldihydropyrenes Probe by Magnetic and Geometric Criteria

Table 1

Comparison of ¹H NMR chemical shifts (calculated), % bond fixation of dihydropyrene nucleus, and % aromaticities of five membered heterocycles with benzene, calculated through (2).

Entry	Heterocycles	DHP	δ	% bond; fixation	% aromaticity (relative to benzene)
1		1	−6.29
2	Benzene	3	−1.91	59.1	100
3	Pyrrole	12	−3.31	40.3	68.1
4	Thiophene	18	−4.16	28.8	48.9
5	Oxazole	20	−4.8	20.2	34.1
6	Isoxazole	21	−3.51	39.6	63.5
7	Thiazole	22	−4.59	23.0	38.9
8	Isothiazole	23	−3.99	33.8	59.1
9	Pyrazole	24	−2.52	50.9	86.1
10	Imidazole	25	−3.81	33.5	56.9
11	Oxadiazole	26	−3.59	36.8	62.2
12	Triazole	27	−2.91	48.4	81.8