Table 1. The synthesis yields of oligoribonucleotides containing N⁶-alkyladenosines via post-synthetic modification of precursor form of oligonucleotides.

	UACR6AUGUA		UR6ACAUGUA		UACAUGUR6A		ACAUGUR6A
	Yielda	MSb	Yielda	MSb	Yielda	MSb	Yielda	MSb
R = H-	64%	2494.99					74%	2188.35
R = methyl-	47%	2508.92	40%	2508.93	51%	2508.61	49%	2202.32
R = neopentyl-	51%	2564.87	47%	2564.93	58%	2564.90	69%	2258.49
R = 1-methylpropyl-	72%	2550.88	42%	2550.90	77%	2551.05	75%	2244.46
R = 1-methylbutyl-	71%	2565.01	61%	2564.95	51%	2564.84	91%	2258.52
R = isopentyl-	45%	2564.94	52%	2564.78	51%	2564.78	55%	2258.47
R = isopentenyl-	56%	2562.92	41%	2563.75	25%	2563.30	65%	2256.11
R = propargyl-	39%	2532.98	40%	2532.64	49%	2532.81	42%	2226.46
CCGGUCmUCCAXAACCGG
	X = A		X = m6Ac		X = i6Ac
	34%	5398.72	29%	5413.92	13%	5467.45

^aBased on C-18 HPLC analysis.

^bMeasured molecular weight of the oligoribonucleotides.

^cObtained from modified phosphoramidites.