Table 2 Geometrical parameters for γ-spirolactams 1b (Å, °)

6-membered ring

 Bond lengths

1.5188(19)–1.5413(15)

1.5237(15)–1.5465(14)

 Bond angles

109.74(10)–114.24(10)

109.08(8)–112.71(9)

 Puckering: q/θ/φ

0.5500(14)/174.57(15)/29.8(2)

0.5676(12)/176.49(12)/208(2)

 Torsion angles

49.00(14)–57.57(14)

52.52(12)–57.52(12)

5-membered ring

 C1–N1

1.3314(15)

1.3316(14)

 C–C–C

100.79(9)–108.71(10)

102.30(8)–109.09(9)

 C1–N1–C2

114.37(10)

114.1(1)

 Puckering: q/φ

0.2995(14)/282.7(2)

0.2546(12)/108.2(3)

 Torsion angles

2.56(13)–29.11(12)

0.75(13)–24.63(12)

6- to 5-memb. ring

 Dihedric angle

81.806(43)

81.007(42)

Torsion angles

 C1–C4–C5–C6

− 73.02(13)

− 177.14(8)

 C1–C4–C9–C8

73.72(13)

− 176.63(8)

 C3–C4–C9–C8

− 176.41(10)

70.74(11)

 C3–C4–C5–C6

173.04(10)

− 68.60(1)

Lactam ring plane

 Max. deviation (C4)

− 0.0299(10)

0.0208(9)

 Distance to O1

− 0.3384(19)

− 0.2321(18)

 Distance to N1

0.4900(16)

0.3764(14)

 Distance to C2

0.7795(19)

0.6460(19)