Fulvenes amino

The various transitions of triafulvenes to pentafulvenes achieved by addition of electron-rich double bonds is complemented by the reaction of triafulvenes with ynamines and yndiamines299, which gives rise to 3-amino fulvenes 539. This penta-fulvene type deserves some interest for its merocyanine-like inverse polarization of the fulvene system and its formation is reasonably rationalized by (2 + 2) cycloaddition of the electron-rich triple bond to the triafulvene C /C2 bond (probably via the dipolar intermediate 538) ... 

In contrast to the usual (4 + 2) diene reactivity of fulvenes 3-amino fulvenes 539 in some cases are capable of expanding the five-membered ring to heptafulvenes 541 by addition of acetylene dicarboxylate in a (2 + 2) fashion299. ... 

In order to avoid the presence of stereoisomers, a further pathway including a carbolithiation reaction delivering achiral titanocene dichlorides was explored. Different aryl or heteroaryl lithium species were reacted with 6-bis-/V,/V-di methyl -amino fulvene and therefore, the intermediate lithium cyclopentadienide and the resulting 6-bis-/V./V-dimethylamino-functionalised titanocene dichlorides become achiral. 

In several synthetic studies, cyclopropane derivatives were used as synthones or building elements for ring enlargement steps, e.g. reaction of enamines with cyclopropenone [65], synthesis of 2,3-dihydro-l,4-diazepine by thermal isomerization of 1,2-diamino-cyclopropanes [32] [66], and preparation of 3-amino-fulvenes from methylencyclopropenes with alkynamines [67]. 

As confirmation of an inert radical production mechanism, iodine compounds are particularly effective because of the production of I atoms. However, there are big deficiencies in our understanding of the details of anti-knock chemistry. This is illustrated by the large differences in antiknock effectiveness shown in MacKinven s measurements between substances with apparently very similar composition [27]. As shown in Table 7.3, some of the methyl substituted diphenyl oxalates are quite good antiknocks, with up to 1.1 times the molar effectiveness of NMA. But another is pro-knock. The mechanism responsible for this structure/property dependence is not known. More recently, high effectiveness has been reported for ashless materials related to dialkyl amino fulvenes [28-31], but no credible mechanisms have been published. No ashless anti-knocks have proved sufficiently cost-effective to be used commercially. 

Wenn vinylogc Aldiminium-Salzc und Amino-fulvene Zwischenprodukte in der Synthese polycyclischer Kohlenwasserstoffe (z. B. in der Azulen-Reihe) sind, wird auf die Hydrolyse zu den Aldehyden haufig verzichtet. 

A methylplatinum complex with a siloxo ligand has been prepared by the metathesis reaction of a chloro(methyl)-platinum complexes with Na[SiOPh3]/ A dinuclear Pt complex with bis(trimethylsilyl)methyl ligands and bridging chloro ligands 52 reacts with /-butyl isocyanide and then with NaCp to produce the platina(amino)fulvene 53 via addition of Cp to the coordinated isonitrile and migration of the hydrogen atom (Equation (15))/ ... 

Cho and coworkers report a 1,3-dipolar cycloaddition [52] of amino-fulvenes 227 to aliphatic or aromatic hydrazonyl chlorides 226 in the presence of silver carbonate, a method which provides a facile synthesis of the cyclopenta[(i]pyridazines 228 (Scheme 7.52) [53]. A plausible intermediate, nitrile imine 228, was found to react with 227 in the presence of KI and silver carbonate and yield the cyclopenta[[Pg.277]

Compounds of special interest whose preparation is described include 1,2,3-benzothiadiazole 1,1-dioxide (a benzyne precursor under exceptionally mild conditions), bis(l,3-diphenylimida-zolidinylidene-2) (whose chemistry is quite remarkable), 6-(di-methylamino)fulvene (a useful intermediate for fused-ring non-benzenoid aromatic compounds), diphenylcyclopropenone (the synthesis of which is a milestone in theoretical organic chemistry), ketene di(2-melhoxyethyl) acetal (the easiest ketene acetal to prepare), 2-methylcyclopentane-l,3-dione (a useful intermediate in steroid synthesis), and 2-phenyl-S-oxazolone (an important intermediate in amino acid chemistry). 

An important ancfllary study with signifrcant synthetic implications revealed that electron-rich dienes attached to fulvenes by a multicarbon chain also exhibited a high degree of preference for forming the corresponding [6 -i- 4] adducts. For example, when substituent X in compound (60) was either diethyl-amino or trimethylsiloxy, the [6 -I- 4] adduct (61) was the major product-type isolated. However, if no substituent was present on the diene portion of the molecule, a mixture consisting of [6 -i- 4], exocyclic [4 -I- 2] (62) and endocyclic [4 -I- 2] (63) cycloadducts was obtained. ... 

A further illustration of the electronic influence of substituents on the course of reactions with 1,3-dipoles can be seen in the cycloaddition of an amino-substituted fulvene to benzonitrile oxide. Adduct (76) was obtained in 60% yield when the electron-rich dipolarophile 6-dimethylaminofulvene was exposed to benzonitrile oxide. The structure of the resultant product can be conveniently explained by an initial [6... 

The Fmoc amino acyl resin (4-8 mg) in a 10-mL polypropylene syringe fitted with a polyethylene disc was stirred or shaken in piperidine/DMF (3 7,1 mL) for 30 min. MeOH (5mL) was then added and the soln was filtered and diluted with MeOH up to a total volume of 25 mL. The resultant fulvene-piperidine adduct has a characteristic UV absorption at 301 nm (e = 7 800 M cm ). For reference, a piperidine/DMF/MeOH (0.3 0.7 24) soln was prepared and the result was compared to a free Fmoc amino acid soln of known concentration treated under identical conditions. The loading (mmol g or pmol mg ) = (A301 X 0.025 L x 10 pmol/mol/7800 M cm x 1 cm x mg of resin). 

The amino group of 6-(dimethylamino]fulvene is itself readily replaced by nucleophilic attack. The following reactions serve as examples [73,247] ... 

With these reagents the presence of an amine substituent on the 6-carbon atom markedly facilitates bromination [246]. This is an example of the way in which 6-amino groups activate the cyclopenta-diene ring to electrophilic attack these fulvenes can be regarded as enamines. Another example is provided by the ready formylation... 

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