sulfonic acid functionalized sba-15 (sba-pr-so3h) with pore size 6 nm as an efficient heterogeneous nanoporous solid acid catalyst exhibited good catalytic activity in the biginelli-like reaction in the synthesis of spiroheterobicyclic rings with good yield and good recyclability. spiro-pyrimidinethiones/spiro-pyrimidinones-barbituric acid derivatives were synthesized in a simple and efficient ...

The title compound, C(33)H(34)N(4)O(2)S·CH(3)OH, was prepared as a spiro-lactam ring formation of rhodamine 6 G dye for comparison with a ring-opened form. The xanthene and spiro-lactam rings are approximately planar [r.m.s. deviations from planarity = 0.122 (3) and 0.072 (6) Å, respectively]. The dihedral angles formed by the spiro-lactam and thio-phene rings with the xanthene ring system are ...

Spiro ring systems have two or more rings linked by one common atom. Several different methods are used to name such systems. Rules A-41, A-43, B-b and B-12 (Nomenclature of Organic Chemistry, 1979) describe the basics of how to name these compounds. The alternative methods in rules A-42 and B-i 1 are abandoned. This document describes the nomenclature in greater detail and extends it to cover ...

The title compound, C(27)H(40)O(4), was obtained from the oxidation of (25R)-3b-hydr-oxy-5a-spiro-stan-12-one (Hecogenin) by Jone's reagent. The mol-ecule contains six alicyclic and heterocyclic rings, all trans-fused, among which four six-membered rings adopt similar chair conformations while two five-membered rings assume an envelope conformation.

The title compound, C(35)H(35)ClN(4)O(3), resulted from a spiro-lactam ring closure of rhodamine B dye. The xanthene ring system is approximately planar [r.m.s. deviation = 0.050 (9) Å for the xanthene ring]. The dihedral angles formed by the spiro-lactam and 5-chloro-2-hy-droxy-benzene rings with the xanthene ring system are 87.9 (7) and 79.1 (7)°, respectively.

The title steroid, C34H50O6S, is an inter-mediate on the synthetic route between diosgenin and brassinosteroids, which possess the A ring modified with the 2α,3α-diol functionality. The polycyclic spiro-stan system has the expected conformation, with six-membered rings adopting chair forms and the five-membered rings envelope forms (flap atoms are the methine C atom in the C/D-ring junction and...

In the title compound, C(38)H(42)N(4)O(4)·C(2)H(6)O, prepared via a spiro-lactam ring-formation reaction in a rhodamine dye, the xanthene ring system is approximately planar (r.m.s. deviation = 0.0014Å) and subtends dihedral angles of 88.10 (3) and 86.92 (4)° with the spiro-lactam (r.m.s. deviations = 0.0012 Å) and benzene rings, respectively. The crystal structure consists of chains parallel t...

In the title compound, C36H31NO4, two spiro links connect the methyl-substituted pyrrolidine ring to the ace-naphthyl-ene and cyclo-hexa-none rings. The cyclo-hexa-none ring is further connected to the dioxalane ring by a third spiro junction. The five-membered ring of the ace-naphthylen-1-one ring system adopts a flattened envelope conformation with the ketonic C atom as flap, whereas the diox...

The title compound, C(35)H(36)N(4)O(4), was prepared as a spiro-lactam ring formation of rhodamine B dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The r.m.s. deviation from planarity is 0.064 (6) Å for the xanthene ring. The dihedral angles formed by the spiro-lactam and 2,4-dihydroxy-benzene rings with the xanthene ring system are 86.6 (9) and 88...