Spiro compound

Spiro compounds ( spirans from Latin spira = winding, pretzel ) are polycyclic organic compounds whose rings are connected at only one atom. Spiro compounds are a class of organic compounds. The rings of the spiro compounds can be both identical and different. The atom to which the two rings are linked is called the spiro atom. It may be a carbon, but also a heteroatom. The smallest spiro compound is spiropentane.

Are more spiro atoms in a molecule, it is called Dispiranen, Trispiranen etc.

Nomenclature of spiro compounds

Allen Spiro Spiro compounds the syllable is preceded by, followed in square brackets - [ ] - the number of ring atoms of the smaller and the larger ring ( without the spiro atom counting ) and append to the name of the nomenclature. The numbering starts with a adjacent to the spiro atom atom of the smaller ring and continues through the ring to the spiro atom away.

General: substituent -spiro [. Atoms in the smaller ring * atoms in the greater ring * ] Family Name

• The ring size is specified without a spiro atom.

Chirality

Some spiro compounds exhibit axial chirality (without chirality ). You already occurs when the two "U " at the spiro atom are the same, but have distinct beginnings and ends. Although the substitution pattern on carbon is C ( AABB ), the compound C (A - B) 2 is chiral. When determining the configuration according to CIP rules, the question of priority of A over B or vice versa plays no role: you impart desired a radical (eg, A) has the higher priority, and one of the two brackets (eg 1 instead of 2) a slightly higher priority and then determine based on the priority sequence A1 > A2 > B1 > B2, the configuration ( aR or aS, a = axial); the result is independent of the allocations.

In cases with distinguishable brackets ( such as A and B above) is determined according to the classical style, the priority order of the four different residues and from the configuration.

Is this spiroatom no chiral center, but the connection still chiral, so there is a chiral axis that passes through the central spiro atom.