Dimethylamino dimer

Azafulvene, 6-aryl-6- N, N-dimethylamino-dimerization, 4, 309 1-Azafulvene, 6,6-bis(alkylthio)-synthesis, 4, 310 1-Azafulvene, 6-dialkylamino-reactions... 

Benzazete, 2-p-(dimethylamino)-stability, 7, 279 Benzazete, 2-mesityl-stability, 7, 278, 279 Benzazete, methylthio-synthesis, 7, 283 Benzazete, 2-phenyl-dimerization, 7, 279 IR spectrum, 7, 278 nomenclature, 1, 36 reactions... 

Tlie desulfurization of thiono compounds is another frequently used synthetic approach for the formation of double bonds via carbenoid intermediates. By this methodology, some indigoid 1,3,5,7-tetraazafulvalenes 88 and 90 were synthesized (83BSB781 90JPR949).Tliis dimerization starting from 2,4,5-tris(dimethylamino)imidazolium chloride via the appropriate thione 87 has been realized in the presence of phosphanes or phosphites to... 

Tetraazafulvalenes bearing two pyrazole subunits could be prepared by an original way. Tlius, treatment of benzylidene acetophenone with iso-pentylnitrite leads to an A, A -dihydroxy-bipyrazolyl-A, A -oxide, which in turn can be oxidized to TAF of type 100 (72CC961, 79JOC3211). Another type of oxidative dimerization was observed by the reaction of the electron-rich l-methyl-2,4-bis(dimethylamino)imidazole with silver salts (83TL3563). A bis-cation was isolated in 30% yield in the presence of sodium tetrafluo-roborate an unsymmetrical structure 101 was predicted from its NMR data (Scheme 40). 

Cp derivatives (Scheme 185) to form -oxo-bridged dimeric complexes. The stabilities of the Af,0-bound carbamate intermediates depend mainly on the cyclopentadienyl ring substituents, but there is also a small dependence on the nature of the length of the (dimethylamino)alkyl chain for the C5H4Me systems. ... 

Kitamura and Noyori have reported mechanistic studies on the highly diastere-omeric dialkylzinc addition to aryl aldehydes in the presence of (-)-i-exo-(dimethylamino)isoborneol (DAIB) [33]. They stated that DAIB (a chiral (i-amino alcohol) formed a dimeric complex 57 with dialkylzinc. The dimeric complex is not reactive toward aldehydes but a monomeric complex 58, which exists through equilibrium with the dimer 57, reacts with aldehydes via bimetallic complex 59. The initially formed adduct 60 is transformed into tetramer 61 by reaction with either dialkylzinc or aldehydes and regenerates active intermediates. The high enantiomeric excess is attributed to the facial selectivity achieved by clear steric differentiation of complex 59, as shown in Scheme 1.22. 

Dubac has employed a Stille coupling reaction to synthesize the pyrroles 88 and 89 from stannylpyrrole aldehyde 87 [71]. The latter tin compound was prepared as shown, and related stannylpyrroles were synthesized similarly [72] or using Muchowski s 6-dimethylamino-l-azafulvene dimer lithiation methodology [73]. 

In 1985, Fluck et al. reported that treatment of the P-fluoromethylene-phosphorane 3f with 2 equiv of butyllithium at -95°C gave the 1,1,3,3-tetrakis(dimethylamino)-lA5,3A5-diphosphete 5f in 34% yield.30 The formation of this four-membered ring could result from a [2 + 2] head-to-tail dimerization of the transient phosphinocarbene 2f. However, an alternative... 

Oxidation of enaminone 1 is initiated by electron loss from the dimethylamino moiety leading to radical cation, RH". The following chemical reaction would be an intramolecular cyclization through addition of a hydroxy group on the radical cation site yielding a cyclic radical cation, cRH ". This step is most likely the rate-determining step. The cyclic radical cation then dimerizes... 

In terms of nitration, the system (NaN02 + CF3SO3H) is of no interest. At the same time, dimerization in this system can be attractive. For the last direction, CF3SO3H (or FSO3H) is necessary to produce binaphthyl derivatives more preferentially than nitro compounds (Tanaka et al. 1996). This work was preceded by the observation that the reaction of NO+AICI4 with 1-methyl-, 1,2-dimethyl-, 1,3-dimethyl, or 1,8-dimethylnaphthalenes in liquid SO2 leads to a partial a,a-dimerization (see Borodkin et al. 1993). Ozeryanskii et al. (1998) published the dimerization of l,8-Af,Af-bis(d imethylamino)naphthalene by the action of NOj in CHCI3. This reaction is accompanied by the formation of 4-nitro-l,8-A,A-bis(dimethylamino)naphthalene. Both gronps of anthors consider cation-radicals of the initial substrates as intermediate species. 

Another system that has been investigated by C CP/MAS NMR spectroscopy as a function of different ligands is a-(dimethylamino)benzyllithium (2, Scheme 1) . The DEE complex was proven to exist in the solid state as an rf coordinated dimer . All the studied complexes are of an tf type according to comparison to solution NMR data. However, the actual structure varies as reflected by the shift difference between the two orf/zo-carbons. This difference ranges from 4.4 ppm for the N, N, N, N, N"-pentamethyldiethylenetriamine (PMDTA) complex to 20.3 ppm for the TMEDA complex. 

FIGURE 14. (a) The monomeric PMDTA complex of phenyUithium . (b) The dimeric TMEDA complex of phenylUthium. (c) The tetrameric DEE complex of phenyUithium . (d) The internally coordinated tetramer of 2-[(dimethylamino)methyl]phenyUithium ... 

In a more recent report, a novel dinuclear N,N,0-donor Schiff base-calcium complex [(DAIP)2Ca]2 where DAIP = 2-[2(-dimethylamino-ethylimino)methyl] phenol 76 (Fig. 12) was shown to initiate ROP of L-lactide in a controlled fashion in the presence of benzyl alcohol giving a 96% conversion within 30-60 min at room temperature, yielding polymers with high molecular weight and low PDIs [89]. Taking into account the dimeric molecular structures of hexa- and hepta-coordinated Ca" in the solid state and the kinetic results gained from this study (first order dependency on [LA] a first order dependency on [BnOH] with d[LA]/ df = prop[LA] [BnOH] and a p op constant of 1.95 s ), a coordinatio-... 

When oxygen is removed from a reaction solution of tetrakis-(dimethylamino)ethylene (TMAE), the chemiluminescence decays slowly enough to permit rate studies. The decay rate constant is pseudo-first-order and depends upon TMAE and 1-octanol concentrations. The kinetics of decay fit the mechanism proposed earlier for the steady-state reaction. The elementary rate constant for the dimerization of TMAE with TMAE2+ is obtained. This dimerization catalyzes the decomposition of the autoxidation intermediate. 

A cyclopentadienylmagnesium bromide containing a heteroatom-functionalized substituent at the cyclopentadienyl group has also been structurally characterized. When l-[2-(dimethylamino)ethyl]-2,3,4,5-tetramethylcyclopentadienylmagnesium bromide is recrystallized from dichloromethane, dimeric [(Mc2N(CH2)2)Me4C5MgBr]2 (206) (Figure 88) is obtained. Its X-ray crystal-structure determination reveals a structure in the solid state... 

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