ChemInform Abstract: Condensed Cyclic and Bridged-Ring Systems. Part 13. Synthesis of the Insect Attractant Hydrocarbon, 9a-Carbamorphinan, and X-Ray Structural Analyses of 9a-Carbamorphinan-10-one and 9a-Carba-14α-morphinan-10-one.

1986 ◽  
Vol 17 (47) ◽  
Author(s):  
A. K. CHAKRABORTI ◽  
S. K. ALAM ◽  
P. C. CHAKRABORTI ◽  
R. DASGUPTA ◽  
J. CHAKRAVARTY ◽  
...  
Keyword(s):  
Ring Systems ◽  
X Ray ◽  
Insect Attractant

scholarly journals The influence of exocyclic lone pairs on the bonding and geometry of type A mesoionic rings

2021 ◽  
Author(s):  
Christopher Antony Ramsden ◽  
Wojciech Piotr Oziminski
Keyword(s):  
Ab Initio ◽  
Type A ◽  
Nbo Analysis ◽  
Ring Systems ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bond Model ◽  
Lone Pairs ◽  
Mp2 Calculations ◽  
Good Agreement

AbstractBased on structures determined by X-ray crystallography, ab initio MP2 calculations on type A mesoionic rings give geometries in good agreement with observed values. A study of four mesoionic ring systems, each with exocyclic oxygen, nitrogen or carbon groups, shows that the presence and configuration of exocyclic lone pairs significantly influences the geometry and configurational preference. Using a localised bond model and NBO analysis, these effects are rationalised in terms of an anomeric interaction of lone pairs with the antibonding orbitals of adjacent σ bonds. In agreement with experiment, similar effects are calculated for pyran-2-imines.

The Meisenheimer Rearrangement in Heterocyclic Synthesis. IV. Derivatives of the 2H,6H-1,5,4-Benzodioxazocine and 7H-1,6,5-Benzodioxazonine Ring Systems: X-Ray Crystal Structure of 10-Methoxy-5-methyl-7-phenyl-2,3,4,5-tetrahydro-7H-1,6,5-benzodioxazonine

1988 ◽  
Vol 41 (3) ◽  
pp. 293 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
LM Engelhardt ◽  
IWK Gunawardana ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Ring System ◽  
Heterocyclic Synthesis ◽  
Rearrangement Product ◽  
Ring Systems ◽  
X Ray ◽  
Derivatives Of ◽  
Moderate Yield

Meisenheimer rearrangement of the N-oxides (4) derived from a series of 5-aryl-4-methyl-2,3,4,5-tetrahydro-1,4-benzoxazepines (3) gave rise to eight derivatives (5) of the new 2H,6H-1,5,4-benzodioxazocine ring system. Reaction of 9-methoxy-5-methyl-6-phenyl-3,4,5,6- tetrahydro-2H-1,5-benzoxazocine (6) with 3-chloroperoxybenzoic acid gave an unstable N-oxide (7). A Meisenheimer rearrangement product from (7), 10-methoxy-5-methyl-7-phenyl-2,3,4,5-tetrahydro-7 H-1,6,5- benzodioxazonine (8), the first example of this ring system, was isolated directly in moderate yield on oxidation of (6) with cooling. The crystal and molecular structure of (8) has been determined by X-ray crystallographic methods.

scholarly journals Synthese und Struktur von 3,3-Diorganyl-2,4-dioxa-l,5-dithia- 1,1,5,5-tetraoxid-3-silacyclohexanen und -heptanen / Syntheses and Structure of 3,3-Diorganyl-2,4-dioxa-1,5-dithia-1,1,5,5-tetraoxid- 3-silacyclohexanes and -heptanes

1994 ◽  
Vol 49 (3) ◽  
pp. 309-314 ◽  
Author(s):  
Peter Sartori ◽  
Ralf Jüschke ◽  
Roland Boese ◽  
Dieter Bläserb
Keyword(s):  
Structure Analysis ◽  
Membered Ring ◽  
Ring Systems ◽  
X Ray

AbstractReactions of di-silver-1,n-alkanedisulfonates 1a (n = 1) and 1b (n = 2) with Cl2SiR1R2 lead to the monomerie 3,3-diorganyl-2,4-dioxa-1,5-dithia-1,1,5,5-tetraoxid-3-silacyclohexanes (for n = 1) 2a (R1 = R2 = Me), 3a (R1 = Me and R2= Ph) and 4a (R1 = R2 = Ph) and -heptanes (for n = 2) 2b (R1 = R2 = Me), 3b (R1 = Me and R2 = Ph) and 4b (R1 = R2 = Ph). In the case of 2a-4a a competition reaction is observed leading to the dimerization products 5a (R1 = Me and R2 = Me), 6a (R1 = Me and R2 = Ph) and 7a (R1 = Ph and R2 = Ph). The six-membered ring-systems of 2a-4a are compared with related silanes. An X-ray structure analysis is per­formed for the 3,3-diphenyl-2,4-dioxa-1,5-dithia-1,1,5,5-tetraoxid-3-silacycloheptane (4b).

Base Catalyzed Rearrangement of Isoxazolinyl Heterocycles: Synthesis of Annelated Pyrimidines

1989 ◽  
Vol 42 (12) ◽  
pp. 2161 ◽  
Author(s):  
C Donati ◽  
WK Janowski ◽  
RH Prager ◽  
MR Taylor ◽  
LM Vilkins
Keyword(s):  
Ring Systems ◽  
X Ray

The rearrangement of a number of ethyl 2-(heterocyclic)-5-oxo-2,5-dihydroisoxazole-4-carb-oxylates by mild base is described, leading to new syntheses of the pyrimido [2,1-a] isoquinoline, pyrimido [1,2-a]quinoline, pyrimido [2,1-b] benzothiazole , pyrirnido [1,2-a] pyrimidine, pyrimido [1,2-b]pyridazine and pyrimido [1,2-c] quinazoline ring systems. A mechanism is suggested, and X-ray crystallographic evidence presented for the structure of one of the products, ethyl 2-hydroxy-4-oxo-4H-pyrimido[2,1-a]isoquinoline-3-carboxylate.

Sign in / Sign up

Export Citation Format

Share Document