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

Table 2

DFT-calculated and experimental ¹H NMR chemical shifts (𝛿_H/ppm) for 1 and 2.

Cmpd, conf.		H-2𝛼	H-2𝛽	H-3	H-4𝛼^a	H-4𝛽^a	H-6	H-7	H-8	H-9
	1	4.24	4.10	3.26	3.55	3.67	6.67	6.80	6.81	6.84
	2	4.03	3.70	3.09	3.67	3.30	6.81	6.89	6.87	6.87
	3	3.96	4.25	3.27	4.08	3.65	6.56	6.78	6.66	6.71
1	4	3.92	4.29	3.15	4.04	3.46	6.53	6.77	6.69	6.75
	5	4.61	3.97	3.17	3.46	4.12	6.39	6.72	6.63	6.76
	6	4.26	4.22	2.98	4.21	3.72	6.55	6.84	6.62	6.76
	PWA	4.19	4.07	3.22	3.66	3.63	6.66	6.81	6.78	6.82
	exp. [12]	4.18^b	4.06^b	3.55	3.72^b	3.64^b	6.63^b	6.76	6.65^b	6.76
	1	4.26	3.32	3.40	3.20	2.75	6.79	6.97	6.97	7.10
	2	3.62	4.35	3.87	2.87	3.99	6.53	6.85	6.75	6.89
2	3	4.00	4.56	3.76	3.22	3.37	6.46	6.81	6.74	6.89
	PWA	4.21	3.43	3.45	3.18	2.85	6.76	6.96	6.94	7.08
	exp. [12]	4.25^b	3.86^b	3.93	3.36^b	3.17^b	6.75	6.89	6.82	6.99

Legend: PWA, population-weighted average. ^aIn the case of 2; proR and proS, respectively, for 1. ^bAssignments assumed with respect to the (near) neighboring value.