Dioxaphosphorinane-Constrained Nucleic Acid Dinucleotides as Tools for Structural Tuning of Nucleic Acids

Table 1

Summary of the backbone torsion angles derived from the canonical B_I-, A-DNA duplex structures and of the synthesized D-CNA^a.

Name	Isomer	Torsion angles
		𝛼	𝛽	𝛾	𝛿	𝜀	𝜁
BI-type		g^−	t	g^+	a^+/t	t	g^−/a^−
A-type		g^−	t	g^+	g^+/a^+	a^−/t	g^−
𝛼,𝛽-D-CNA	(𝑅C5′,𝑆𝑃)	g^−	t
	(𝑆C5′,𝑅𝑃)	g^+	t
	(𝑅C5′,𝑅𝑃)	a^+	a^−/t
	(𝑆C5′,𝑆𝑃)	a^−	a^+/t
𝛼,𝛽-P-CNA	(𝑆C5′,𝑆𝑃)	g^+	t
	(𝑅C5′,𝑅𝑃)	a^−/t	t
LNA/𝛼,𝛽-D-CNA	(𝑅C5′,𝑆𝑃)	g^−	t		g^+/a^+
	(𝑆C5′,𝑅𝑃)	g^+	t		g^+/a^+
	(𝑅C5′,𝑅𝑃)	a^+	a^−/t		g^+/a^+
𝛼,𝛽,𝛾-D-CNA	cis	g^−	g^−	g^−
	trans	g^+	c/g^+	g^−/a^−
𝛿,𝜀,𝜁-D-CNA	(𝑆C4′,𝑅𝑃)				a^+/t	g^−	g^−
	(𝑆C4′,𝑆𝑃)				a^+/t	g^−	a^+/t
𝑣2,𝜀,𝜁-D-CNA	(𝑅C2′,𝑆𝑃)				a^+	g^+	g^−
	(𝑅C2′,𝑅𝑃)				a^+	g^+	t
𝜀,𝜁-D-CNA	(𝑆C3′,𝑅𝑃)				c	t	g^+
	(𝑆C3′,𝑆𝑃)				c	t	g^−

^aThe following 6-fold staggered pattern of the torsional angles is used: cis: 0 ± 30° (c), gauche (+) = 60 ± 30° (g⁺), anticlinal (+): 120 ± 30° (a⁺), trans: 180 ± 30° (t), anticlinal (−) = 240 ± 30° (a⁻), and gauche (−) = 300 ± 30° (g⁻). The notation a⁺/t is used to designate a torsion angle on the border of anticlinal (+) and trans.