Spiro linkage

When ring fusions and/or bridges are present in addition to spiro linkages, the fused or bridged units are first named individually (by any of the available methods) and the names are then cited (in square brackets and in alphabetical order) with the prefix spiro- or dispiro-, etc. Points of spiro attachment are indicated between the names of the components, with primes as necessary (examples 64-66). This method is also applicable to structures like (62) and (63) but is more cumbersome. 

A completely different access to molecules with a scissor-like shape is opened up via spiro-linkage. Typical examples following this building principle are the spiro-bifluorenes 22 3) and 23 43 which differ also in the functional groups. In case of the spirocompounds, the flexible hinge is not applicable-and the edges of the molecular scissors are fixed at an angle of 90°. 

Figure 3.13. Molecular glasses based on a spiro linkage.

Heterocyclic components can be given replacement names e.g., 49 would then be named spiro-[3//-l-azaindene-3,r-cyclopenta[2,4]diene]. Both types of method a spiro nomenclature are readily extensible to molecules containing more than one spiro linkage, e.g., 51 and 52. 

This again illustrates the problem of correct citation of hydrogenation. The unsubstituted spiro skeleton is structure a, named as spiro[oxiran-2,3 (2 //)-pyridine], it being necessary to introduce an indicated hydrogen (2 H) to allow for the spiro linkage. The ketone groups are... 

The computational investigation of 37-R and 37-S shows that, even if these molecules are characterized by steric constraints due to the spiro linkage of the two five-member rings, up to four slightly different conformers featuring similar energy were located by the MM/MD procedure. The comparison of the... 

Other spiro-linkages have also been introduced at the C9-position of flu-orenes in attempts to stabilize the emission (Scheme 31). Polymers, e.g., 69, with spirocycloalkyl groups still produce green emission upon annealing [ 104], whereas the polymer 70 with aryl groups at C9 displays stable blue PL and EL [105]. 

Aside from the spiro-linkage one could also think of other sterical groups that... 

The absorption and photoluminescence spectra of both materials are shown in Fig. 12.7 (c,d). The luminescence of p-scxiphcnyl is very similar to the spectrum of the spiro-derivative, only the vibronic sidebands are more pronounced. This shows that aside from the improved morphological stability, the spiro-linkage merely leaves the optical properties of the chromophore unaltered. 

Spiroketals have been obtained by RCM of cyclic ketals 18 without loss of stereochemical integrity at the spiro linkage <04TL5505> and a stereoselective solid-phase synthesis of 6,6-spiroketals has been reported in which aldol reactions of boron enolates are the key feature <04AG(E)3195>. Spiro orthoesters are accessible from thiophenyl ketene acetals and diols (Scheme 5) <04SL2013>. 

All the macrocyclic imines possess several characteristics in common (1) a six- or seven-membered imino ring (2) a cyclohexenyl ring with spiro linkage to the cyclo-imine (except for the prorocen-trolides with condensed rings) (3) para-substitution on the cyclohexenyl ring (4) a macrocycle... 

The new tetracyclic ring system (66), containing a pyrrolo[l,2-6]-l,2,5-benzotriazepine ring bounded by a spiro linkage to the piperidine nucleus, has been synthesized in 40-60% yields by a simple reaction between the aromatic amine (59) and 4-oxopiperidines (63) in the presence of maleic acid, as a catalyst, via the intermediates (64) and (65) (Scheme 11) <92JHC241>. 

Space charge limited current (SCLC), 16-9, 16-19, 19-3 Spectral degradation, 5-22, 5-25-5-27 Spin density wave (SDW), 16-12, 16-14 Spiral morphology, 3-3, 3-7-3-S, 3-10-3-12 Spiro linkages, 5-6, 5-20, 5-22, 5-23, 5-24 Spiro-type oligoarylenes, 5-23, 5-24, 5-30 STABASE, 9-21... 

---