Substituent effects in ring-chain tautomerism of the condensation products of non-racemic 1,2-aminoalcohols with aromatic aldehydes

Crystal structure and Hirshfeld surface analysis of 4-bromo-2-[3-methyl-5-(2,4,6-trimethylbenzyl)oxazolidin-2-yl]phenol

In the crystal, neighboring mol­ecules are linked into layers parallel to the (200) plane via C—H⋯O hydrogen bonds and C—H⋯π inter­actions. van der Waals inter­actions between parallel mol­ecular layers help to strengthen the packing.

The title compound, C₂₀H₂₄BrNO₂, is chiral at the carbon atoms on either side of the oxygen atom of the oxazolidine ring and crystallizes as a racemate. The 1,3-oxazolidine ring adopts an envelope conformation with the N atom in an endo position. The mean plane of the oxazolidine ring makes dihedral angles of 77.74 (10) and 45.50 (11)°, respectively, with the 4-bromo­phenol and 1,3,5-tri­methyl­benzene rings. In the crystal, adjacent mol­ecules are connected via C—H⋯O hydrogen bonds and C—H⋯π inter­actions into layers parallel to the (200) plane. The packing is strengthened by van der Waals inter­actions between parallel mol­ecular layers. A Hirshfeld surface analysis shows that H⋯H (58.2%), C⋯H/H⋯C (18.9%), and Br⋯H/H⋯Br (11.5%) inter­actions are the most abundant in the crystal packing.

A novel type of organometallic 2-R-2,4-dihydro-1H-3,1-benzoxazine with R = [M(η5-C5H4)(CO)3] (M = Re or Mn) units. Experimental and computational studies of the effect of substituent R on ring-chain tautomerism

Novel 2-cyrhetrenyl and cymantrenyl-2,4-dihydro-1H-3,1-benzoxazines.

Enumeration of ring-chain tautomers based on SMIRKS rules

A compound exhibits (prototropic) tautomerism if it can be represented by two or more structures that are related by a formal intramolecular movement of a hydrogen atom from one heavy atom position to another. When the movement of the proton is accompanied by the opening or closing of a ring it is called ring–chain tautomerism. This type of tautomerism is well observed in carbohydrates, but it also occurs in other molecules such as warfarin. In this work, we present an approach that allows for the generation of all ring–chain tautomers of a given chemical structure. Based on Baldwin’s Rules estimating the likelihood of ring closure reactions to occur, we have defined a set of transform rules covering the majority of ring–chain tautomerism cases. The rules automatically detect substructures in a given compound that can undergo a ring–chain tautomeric transformation. Each transformation is encoded in SMIRKS line notation. All work was implemented in the chemoinformatics toolkit CACTVS. We report on the application of our ring–chain tautomerism rules to a large database of commercially available screening samples in order to identify ring–chain tautomers.