Multiple contiguous

Tokoroyama T. Synthesis of Clerodane Diterpenoids and Related Compounds -Stereoselective Construction of the DecaUn Skeleton With Multiple Contiguous Stereogenic Centers Synthesis 2000 611-633... 

Silylene transfer to a -unsaturated esters produces oxasilacyclopentenes and provides a new method for regio- and stereo-selective formation of enolate that can undergo facile and selective Ireland-Claisen rearrangements and aldol addition reactions to provide products with multiple contiguous stereocenters and quaternary carbon centers (Scheme 37). 

Tokoroyama T (2000) Synthesis of clerodane diterpenoids and related compounds - stereoselective construction of the decalin skeleton with multiple contiguous stereogenic centers. Synthesis 611-633... 

There are two digressions. The first describes a convergent strategy to multiple contiguous chiral centers which involves aldol condensation of two sugars. The second reports a procedure for chemoselective activation of the anomeric oxygen. 

Ozeki, M., Ochi, S., Hayama, N., Hosoi, S., Kajimoto, T., Node, M. (2010). One-pot construction of multiple contiguous chiral centers using Michael addition of chiral amine. Journal of Organic Chemistry, 75, 4201-4211. 

While the homestead theory was never seriously considered in the United States experience, it has been recommended as part ot a subsoil privatization program for Latin America. The major attraction is increased economic efficiency Production and management of a contiguous oil and gas resei voir is most efficiently done by one operator, and homesteading creates one owner in place of multiple owners under the rule of capture. 

In recent years Pagani and coworkers have made detailed studies of the problem. In the space available we can only outline their work and interested readers should consult the very detailed papers. The authors have developed special scales of substituent constants for dealing with contiguous functionalities 193. These new substituent constants are a (which seems to be related fairly closely to the ordinary a ), aIB (which bears some relationship to o/, but not that close), and (Tr-, a special delocalization parameter. It is claimed194 that these scales are appropriate for describing interactions between contiguous functionalities, as opposed to literature values which account for remote interactions . Various C—H acidities in gas phase and in solution were successfully correlated by means of multiple regressions on am and chemical shifts for the central carbon in the carbanions. 

A model of such structures has been proposed that captures transport phenomena of both substrates and redox cosubstrate species within a composite biocatalytic electrode.The model is based on macrohomo-geneous and thin-film theories for porous electrodes and accounts for Michaelis—Menton enzyme kinetics and one-dimensional diffusion of multiple species through a porous structure defined as a mesh of tubular fibers. In addition to the solid and aqueous phases, the model also allows for the presence of a gas phase (of uniformly contiguous morphology), as shown in Figure 11, allowing the treatment of high-rate gas-phase reactant transport into the electrode. 

The next question is how can we understand and predict what spin-spin splitting patterns will be observed And how do they give us structural information The important point is that the multiplicity of lines for protons of a given chemical shift often is seen to be (n + 1), in which n is the number of protons on the contiguous carbons. For example, the CH2 resonance of the ethyl group of ethyl iodide is a quartet of lines because of the spin-spin inter-... 

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