Cyclic coupling

W. N. Colier, V. Quaresima, B. Oeseburg, and M. Ferrari. Human motor-cortex oxygenation changes induced by cyclic coupled movements of hand and foot. Experimental Brain Research, 129 457-461, 1999. 

The excellent coordination properties of alkynes with transition metals led to their use as partners for the coupling with a large variety of unsaturated molecules. Two partners such as alkynes and alkenes can produce various modes of C-C bond formation. Linear or cyclic couplings can occur via different pathways, similar to those reported for two C=C bonds couplings (Scheme 1). 

The cyclic coupling of alkynes of the current invention is a modified Glasser reaction and is described (1). 

The dimerization of allenic compounds led to linear or cyclic couplings. The [CpRu(CH3CN)3]PF6-catalyzed reaction of allenic alcohols with acetic acid in the presence of Cu(OAc)2 afforded the corresponding linear dimers with addition of acetate group [111] [Eq. (49)]. An acetoxyruthenacycle formed from an internal and a terminal double bond is proposed as intermediate. 

The rapid reaction of LiMe2Cu with trityl halides in ether produces trityl radicals, as shown by ESR. The reaction with a cyclizable alkyl halide, 6-iodo-l-heptene, produced the cyclic coupled product. Both results are strongly indicative of the intermediate radical formation by a singleelectron transfer pathway. 

A further essential feature of the equations of motion discussed so far is the fact that the functions Fi xi,jc ) in (1.1,11) are generally non-/mear and that the transition probability w (y <— ) in (1.16) is a function of x and This non-hnear structure can be considered as a consequence of the self-consistency principle , i.e. there exists a cyclic coupling or a feedback between causes and effects , where both may be macro variables. For instance, the units of a system may generate a collective field this field reacts on the units in a static or dynamic way creating and stabilizing a certain space-time order of positions, orbits, excitations, etc. of the units. The ordered structures and the collective field then mutually sustain themselves in a self-consistent way. 

As in physics, the non-linear form of the equations expresses a self-consistent structure of the sociological system. This implies that there exists a cyclic coupling between causes and effects in society which can be described as follows ... 

One of the features of this sort of cyclic coupling of causes and effects is that self-accelerating as well as self-saturating processes result. In the normal case the feedback between individuals and the collective field leads to a sustained quasi-stable or evolutionary phase, i.e. a self-consistent collective structure of society. In this case there exists a certain predictability of further development because the space of mutually influencing relevant macrovariables (taken from the socio-political and economic situation) is known and these macrovariables obey a quasi-closed subdynamics. 

The third alternative is a more robust, sensitive and specialized fonn of the first, in that only hydrogen nuclei indirectly spin-spin coupled to in a specific molecular configuration are imaged. In achieving selectivity, the technique exploits the much wider chemical shift dispersion of compared to H. The metliod involves cyclic transfer from selected H nuclei to indirectly spin-spin coupled C nuclei and back according to the sequence... 

On investigating a new system, cyclic voltannnetty is often the teclmique of choice, since a number of qualitative experiments can be carried out in a short space of time to gain a feelmg for the processes involved. It essentially pennits an electrochemical spectrum, indicating potentials at which processes occur. In particular, it is a powerfid method for the investigation of coupled chemical reactions in the initial identification of mechanisms and of intemiediates fomied. Theoretical treatment for the application of this teclmique extends to many types of coupled mechanisms. 

The intramolecular version for synthesizing cyclic and polycyclic compounds offers a powerful synthetic method for naturally occurring macrocyclic and polycyclic compounds, and novel total syntheses of many naturally occurring complex molecules have been achieved by synthetic designs based on this methodology. Cyclization by the coupling of an enone and alkenyl iodide has been applied to the synthesis of a model compound of l6-membered car-bomycin B 162 in 55% yield. A stoichiometric amount of the catalyst was used because the reaction was carried out under high dilution conditions[132]. 

Regiocontrolled q- or / -alkenylation and arylation of cyclic enones are possible without protection of the ketone by applying the coupling reaction of the Q- or /3-halo enones 607 and 608 with aryl and alkenylzinc reagents[468,469]. 

The 3.8-nonadienoate 91, obtained by dimerization-carbonylation, has been converted into several natural products. The synthesis of brevicomin is described in Chapter 3, Section 2.3. Another royal jelly acid [2-decenedioic acid (149)] was prepared by cobalt carbonyl-catalyzed carbonylation of the terminal double bond, followed by isomerization of the double bond to the conjugated position to afford 149[122], Hexadecane-2,15-dione (150) can be prepared by Pd-catalyzed oxidation of the terminal double bond, hydrogenation of the internal double bond, and coupling by Kolbe electrolysis. Aldol condensation mediated by an organoaluminum reagent gave the unsaturated cyclic ketone 151 in 65% yield. Finally, the reduction of 151 afforded muscone (152)[123]. n-Octanol is produced commercially as described beforc[32]. 

Rectification accounts for systematic measurement error. During rectification, measurements that are systematically in error are identified and discarded. Rectification can be done either cyclically or simultaneously with reconciliation, and either intuitively or algorithmically. Simple methods such as data validation and complicated methods using various statistical tests can be used to identify the presence of large systematic (gross) errors in the measurements. Coupled with successive elimination and addition, the measurements with the errors can be identified and discarded. No method is completely reliable. Plant-performance analysts must recognize that rectification is approximate, at best. Frequently, systematic errors go unnoticed, and some bias is likely in the adjusted measurements. 

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