Preparation and Structure Classification of Heteraspiro[m.n]alkanes

Abstract

The fundamental spirane framework consists of two monocyclic rings linked in an orthogonal relationship by a common ring atom. In spiranes with no annular heteroatom, four carbon atoms are bonded directly to the quaternary spirocarbon. The spirocarbon may be the site of a stereogenic centre and stereoisomerism. This review covers families of spiranes where one or both rings carry additional annular heteroatoms, mainly N, O or S. The heteroatoms are indicated by replacement prefixes. In general, the term 'hetera' denotes a nonspecified annulated heteroatom which may be N, O, or S. The presentation is arranged with preference for the size of the monocyclic rings and thereafter the nature of the annular heteroatoms.In general, rigid spirocyclic structures provide wide variations of spatial disposition of the functional groups. When the spirane skeleton consists of small-or medium-sized rings, a rigid structure results that also confers stiffness onto molecules in which the spirane may be embedded. The rigidity of such systems provides a stiff framework for the attachment of pharmacophoric groups, or a rigid framework for metal coordination. Reference is made to a limited number of studies of physico-chemical properties of small-ring systems. Nitrogen-containing systems are most common. 1 Introduction and Definitions 2 Heteraspiro[2.m]alkanes 3 Heteraspiro[3.m]alkanes 4 Heteraspiro[4.m]alkanes 5 Heteraspiro[5.m]alkanes

The first example of the stereoselective synthesis and crystal structure of a spirobicycloquinazolinone based on (–)-fenchone and anthranilamide

“…Spirocyclic compounds are molecules containing two rings linked by a common C atom (spiroatom). Since the discovery of this class of compounds, it has been found that similar structures exist in many natural and synthetic products (Smith & Baxendale, 2015;Undheim, 2014). Spirocyclic compounds containing a chiral spiro-quaternary C atom are especially attractive to organic chemists (Galliford & Scheidt, 2007).…”

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

“…7 We recently published a review on heteraspiranes with annular heteroatoms where no heteroatom is directly attached to the quaternary spirocarbon. 8 The most recent report deals with α-monoheteraspiranes where one heteroatom is directly bonded to the spirocarbon. 9 The present review deals with families of tri(α-hetera)spiranes where the three heteroatoms (O, S or N) are directly bonded to the spirocarbon.…”

Stereoselective Reactions in Preparation of Chiral α-Hetera­spiro[m.n]alkanes

“…A review was published in 2014 on heteraspiranes with annular heteroatoms where no heteroatom is directly attached to the quaternary spirocarbon. 1 This review discusses families of α-monohetera-spiranes where one heteroatom is directly bonded to the spirocarbon. One or both spirane rings may contain additional annular heteroatoms (N, O, S) without direct bonding to the carbon center.…”