Spirobiindan

Dimethylaminobenzoates have also been used to establish the absolute configuration of diols in the presence of an aromatic chromophore, including metabolites of benzo[a]pyrene163 and precocene I164, as well as the cis-dihydrodiol derived from 12-methylbenz[a]anthracene165 and diastereomeric 2,2 -spirobiindane-l,l -diols166. 

Cobalt(II) complexes prepared in situ from (AcO Co and two novel chiral spiro nitrogen-containing ligands, 7,7/-bis(2-pyridinecarboxamido)-l,l/-spirobiindane (SIPAD) and 7,7/-bis(2-quinolinecarboxamido)-l,l/-spirobiindane (SIQAD), are efficient cata- lysts for the asymmetric Michael addition of malonates to chalcone derivatives. The alkylation products were obtained in high yields with moderate enantioselectives.169... 

Other reactions occur at even longer times. Indans and indanyl cations form first these are the final products for alkyl-substituted a-methylstyrenes. However, further reactions of the p-methoxy derivative leads to formation of spirobiindan and anisol [Eq. (11)]. 

However, the equilibrium monomer concentrations of disubstituted alkenes is measurable. The equilibrium constants for dimerization, tri-merization, and polymerization of a-methylstyrene have been determined as a function of temperature under anionic conditions [12] similar values should be obtained under cationic conditions. Unfortunately, the equilibrium position can t be determined directly under cationic conditions due to the irreversible side reactions of isomerization and indan and spirobiindan formation (Section II. A). The equilibrium monomer concentrations of isobutene and isopropenyl vinyl ethers should also be relatively high, albeit lower than those of a-methylstyrenes. However, the true equilibrium can t be reached with these monomers due to irreversible side reactions, and reliable data are therefore not available. Nevertheless, the ceiling temperature of isobutene polymerization is apparently between 50 and 150° C. 

The effectiveness of several different protic acid catalysts was evaluated under various reaction conditions. The treatment of 185 and excess 167 with Nafion at 100° C resulted in the formation of 6,6 -dihydroxy-3,3,3 3 -tetramethyl-l,l -spirobiindan (190) [Eq. (19)]. This product was also obtained when CH3SO3H was used as the acid catalyst at 65° C [Eq. (20)]. 

In 2002, Zhou and coworkers designed and synthesized a new type of spiro phosphoamidites 1 based on spirobiindane backbone [20]. These spiro monopho sphoramidite ligands 1, especially SIPHOS (la), showed high enantioselectivities (up to 99.7% ee) in the rhodium catalyzed asymmetric hydrogenation of arylenamides (Scheme 8.4) [15]. The reaction was performed under typical conditions with rhodium catalyst, usually produced in situ from [Rh(COD)2 BP.i with 2 equiv of... 

The high rigidity is the key feature of the chiral spirobiindane ligands, which exhibited special advantages in many asymmetric reactions. One example is the Cu complex of chiral spiro bisoxazoline ligand (S, S,S)-23a (R=Ph). Zhu et al. [33] analyzed the X-ray structures of Cu(I)-(5, 5,5)-23a with various anions (PF, C10 , and BArp). All the complexes have an unexpected binuclear Cu structure, as shown... 

Figures Chiral ligands with I, I -spirobiindane backbone...

Diindane 12 (l,2 -spirobiindane) maybe considered the simplest congener of the irregular centropolyindanes. One of the benzene rings is fused with one of the neopentane carbon atoms, thus blocking it against annelation of further... 

Spirobiindane 3 and Cs-diindane 34 (czs-4b, 9,9a, 10-tetrahydroindeno[l,2-a]indene), the parent of 4, constitute the diindane building blocks of all higher centropolyindanes. The synthesis and chemistry of 3 has been well established [61], and only few papers appeared in recent years [62]. Some attempts to use derivatives of 3 to construct centropolyindanes have all failed [29,37]. In contrast, the derivatives of mono-/zzso-diindane 4 or its parent compound 34 have... 

Notably, use of chlorobenzene as a solvent instead of xylenes allowed us to synthesize tetraindane 112 in moderate yield [49] (Scheme 22). This hydrocarbon contains two Cs- and one C2-diindane units fused in a two-fold angular way (as well as two l,2 -spirobiindanes 12) and it appears to be more strained than expected. According to our schematics for centropolyindanes, 112 has to be classified as a (two-fold) irregular centrotriindane. In this view, both 111 and 112 represent the first derivatives of the irregular triindane 17. 

Tricarbonylchromium complexes of several diindanes and triindanes have been prepared and their structural details have been determined by X-ray structure analysis. In addition to the Cr(CO)3 complexes of 2,2 -spirobiindane [125] and its derivatives, which were used as diastereomeric synthetic intermediates [126], the mono- and bis-complexes of Cs-diindane 34 [127] and its C2-symme-tric isomer (cf. 14 and 106) [128] have been studied. Previously, the stereoisomer-ic mono-Cr(CO)3 complexes of 4 as well as some analogues were synthesized [68]. Also, several Cr(CO)3 complexes of alkylated C2-dihydrodiindenes have been reported [129]. Triptindane 5 has been converted into a mono-, two bisand the tris-complex270 (Scheme 57) [130],and 10-methyltribenzotriquinacene 7 furnished a total of six different Cr(CO)3 complexes. Among these the two possible stereoisomeric tris-complexes were characterized [131]. Recently, cationic tricarbonylmanganese complexes of several centropolyindanes have been prepared and their structures characterized [132]. 

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