Table 1.

NMR-data of Compound Q

Position	δ, ppm†			J, Hz‡
	δ13C	δ15N	δ1H	JHH	Jcc
C-7α*	17.1		1.12		37
C-6α*	21.2		1.22		40
C-7α	35.0		3.00§, 3.30§	24	40
C-6α	37.0		3.07, 3.36	25	43
C-1′*	46.4		3.09, 3.53		42
C-1′	49.9		4.58, 4.01		39
C-6*	54.4				36
C-7*	59.9				38
C-5′ or 5′*	62.1		3.45–3.20		40
C-5′ or 5′*	62.2		3.45–3.20		41
C-2′	68.2		4.01		40
C-4′	71.4		3.52		42
C-2′*, C-3′*,	71.6		3.50–3.25		nd
C-4′*	72.0
	72.6
C-3′	73.0		3.50		42
C-4a*	92.6				75
C-4a	133.5				75, 61
C-6	137.6				56
C-8a*	145.4				80
C-7	147.3				55
C-8a	150.6				nd
C-2	150.6
C-2	157.8
C-4*	160.8				80.5
C-4	162.3				77.5
N-5		334.6
N-1		190.7
N-8		184.9
N-3		159.8¶
N-3*		147.0¶
N-1*		123.4¶
N-8*		88.8
N-5*		49.9¶

The ribityl signals are tentatively assigned by comparison with chemical shifts of 6,7-dimethyl-8-ribityllumazine (see also Table 3). For atom numbering, see Fig. 9. nd, not determined because of signal overlapping. 

^† Chemical shifts, referenced to external trimethylsilyl propane sulfonate. 

^‡ HH coupling constants are extracted from hmoc experiments and CC couplings are extracted from ¹³C spectra of ¹³C-enriched Compound Q. 

^§ Exchangeable with D₂O. 

^¶ Signal phase is modulated by ¹H decoupling.