Ring-In-Molecule

Rings in molecules make a difference, and we have already devoted the whole of one chapter (33) and most of another (18) just to the structure and reactions of rings. In those chapters, the message was that rings have well-defined conformations, and that well-defined conformations allow reactions to be stereoselective. 

Yonemitsu and his coworkers found that the intramolecular photoaddition of chloroacetoamide derivatives with an electron donating aromatic ring in molecules gives the cyclic amide compounds in water [69], However, the photoreaction in or nic solvents proceeds via the exciplex to give the different cyclized products. 

Draw molecule A in what should be the low-energy conformation. Briefly discuss the conformation for the highlighted rings in molecule A. Also discuss the conformational preference (axial or equatorial) for all both methyl groups as well as the hydroxyl. 

The lupin(e) alkaloids are a group of alkaloids possessing quinolizidine ring or piperidine ring in molecules. This group of compounds comprises ca. 200 structurally related alkaloids that represent 2% of the 10000 known alkaloids in nature [1]. These alkaloids are distributed in the family Leguminosae, subfamily Papilionoideae (Lotoideae, Faboideae, Papilionatae), in particular, in the species in the more primitive tribes of the Papilionoideae, but not in the other subfamilies Caesalpinioideae or Mimosoideae. 

Among molecules 2-8 the oxo derivative 2 is the best studied by experimental and theoretical methods. It was established that cyclohexene ring in molecule 2 adopts a sofa conformation according to NMR [38, 39], microwave [40], Raman [41] and IR [42 5] spectroscopic studies. The same results were obtained from theoretical calculations by molecular mechanics [46,47] and quantum chemical HF/6-3 lG(d,p) and MP2/6-31G(d,p) methods [48]. More detailed analysis of cyclohexenone conformation by MP2/6-31 lG(d,p) method indicated that its conformation may be described as slightly distorted sofa [49]. Similar conclusion was made based on results of X-ray diffraction study of inclusion complex [50] containing molecule 2. 

LDM-Based Similarity of Rings-in-Molecules (RlMs) to Benzene as a Measure of Local Aromaticity... 

Scheme 3.2 Molecular set considered in the study of rings-in-molecules (RIMs) similarity distance from benzene...

Sumar I, Cook R, Ayers PW, Matta CF (2016) Aromaticity of rings-in-molecules (RIMs) from electron localization-delocalization matrices (LDMs). Phys Scripta 91 013001 (pp 13)... 

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