Spiro-complexes

Treatment of 460 with triethylamine in DMSO gave 15% of 461. This compound was also obtained from spiro complex 462 formed from 460 by the action of potassium rerr-butoxide (Scheme 73) (74ZOR826, 78ZOR105). 

Trinitrochlorobenzene (76) treated with 1,3-propanedithiole and one equivalent of a base provided compound 479 and its treatment with additional base was reported to provide only small yields of benzodithiepine 480 (74CC672). A more recent work described that good yield (80%) of 480 was obtained by a treatment of 479 with triethylamine in benzene (76ZOR844). Similar treatment of 81 provided first spiro complex 481, which refluxed in acetone in the presence of triethylamine gave good yield of the denitrocyclization product 482 (Scheme 77) (92ZOR1496). 

Reactions of the branched tetraalkynylsilanes 115 (RC=C)4Si (R = tBu, Ph, Me3Si) with the metallocene sources 1 or 2a lead, through twofold migration and C—C coupling of the alkynyl groups, to a novel type of dinuclear carbon-rich spiro-complexes 116 [57]. 

A pronounced chirality effect on the chemical reactivity of ylid complexes is to be expected from propeller-type ligands with a C2 rotation axis. In a first attempt to synthesize pertinent examples, a spirobicyclic ylide 1 was designed (11) and converted into a novel lithio-derivative 2, which on reaction with metal halides yields multi-spiro complexes of unusual geometries ... 

Bemasconi and Gehriger (1974) have presented evidence in a recent study of spiro complex formation (33) which indicates that... 

Kinetic study of the ring opening of the two spiro complexes [15] and [16] has also been reported (Crampton and Willison, 1974), and... 

The reaction between Sil4 and NaCo(CO)4 (equation 49) gives cobalt cluster (39) in which the silicon is coordinated to four cobalt atoms, the Si-Co(CO)3 distances averaging 2.218 A and the Si-Co(CO)4 distance being 2.288 The reaction of SiH4 with Co2(CO)g (equation 50) gives the spiro complex (40) in which the Si-Co distance averages 2.288 Similarly, the reaction between SiLt and NaM(CO)5 (M = Mn or Re) leads to tri- and tetra-substituted products (equation 51). ... 

In a similar manner to the cobalt case, SiH4 reacts with Fc2(CO)9 (equation 52) to give a spiro complex (41) containing no bridging COs and with an average Fe-Si distance of 2.345 A. ... 

Reversible double Smiles rearrangement through intermediate formation of tautomeric Meisenheimer spiro-complexes was observed in the system of l-methylamino-3-picryloxy-2-propanol [18] (Scheme 9). 

Diethylmagnesium and B-alkylboraindane react via a partially isolable intermediate (LXIX) to form crystalline spiro complexes (LXX) (75). 

The reactions of the branched tetraalkynylsilanes (RC = C)4Si (R = Ph, Bu, SiMes) with the metallocene source Cp2Ti(ri -Me3SiC = CSiMe3) and Cp2Zr(THF)(ri -Me3SiC = CSiMe3) led to complexes 44. These gave a novel type of binuclear carbon-rich spiro complexes and the conversions proved to be independent of the metals, the substituents R and the stoichiometries em-ployed. ... 

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