Differentiation between 6- and 7-Membered Rings Based on Theoretical Calculation of NMR Parameters

Table 4

DFT-calculated and experimental homonuclear ¹H-¹H NMR spin-spin (scalar) coupling constants (𝐽_H,H/Hz) for 1 and 2 in the alicyclic ring.

Cmpd,; conf.		H-2𝛼,; H-2𝛽	H-2𝛼,; H-3	H-2𝛽,; H-3	H-3,; H-4𝛼^a	H-3,; H-4𝛽^a	H-4𝛼,; H-4𝛽^a	H-2𝛼,; H-4𝛼^a	H-2𝛼,; H-4𝛽^a	H-2𝛽,; H-4𝛼^a	H-2𝛽,; H-4𝛽^a
	1	−9.50	7.54	2.82	1.19	2.79	−10.01	−0.13	−0.69	0.16	−0.25
	2	−9.34	1.28	2.72	9.46	4.28	−9.14	−0.02	0.27	−0.65	−0.26
	3	−9.38	1.95	2.41	9.13	3.15	−5.94	−0.12	0.26	−0.66	−0.16
1	4	−9.37	1.91	2.32	9.78	4.85	−10.48	−0.07	0.17	−0.63	−0.45
	5	−8.71	2.12	1.98	4.14	9.31	−5.62	−0.62	−0.26	0.68	−0.62
	6	−9.24	1.84	2.32	0.90	3.72	−10.82	0.24	0.01	0.10	2.36
	PWA	−9.42	5.48	2.70	3.60	3.38	−9.34	−0.12	−0.38	−0.05	−0.17
	exp. [12]	−10.8	5.9^b	2.9^b	4.9^b	7.1^b	−10.7	no	no	no	no
	1	−10.00	3.46	0.85	4.52	1.29	−9.97	1.53	0.04	−0.03	0.44
	2	−10.88	7.76	7.08	2.02	2.32	−10.98	−0.44	−0.35	0.23	−0.55
2	3	−10.55	0.93	2.61	7.91	7.46	−11.34	−0.41	0.38	−0.36	−0.48
	PWA	−10.08	3.62	1.29	4.51	1.60	−10.08	1.34	0.03	−0.03	0.35
	exp. [12]	−12.3	3.8^b	2.0^b	4.9^b	2.4^b	−12.9	1.4	no	no	no

Legend: no, not observed; PWA, population-weighted average. ^aIn the case of 2; proR and proS, respectively, for 1. ^aAssignments assumed with respect to the neighboring value. ^bAssignments arbitrary and can be interchanged with the neighboring value.