In situ transfer

Bergman S, Kane D, Siegel IA, Ciancio S (1969) In vitro and in situ transfer of local anaesthetics across the oral mucosa. Arch Oral Biol 14 35 13... 

However, such a marked ligand effect of the ester moiety was not observed in the case of methyl acetoacetate (23.5% e.e.)153 or ethyl benzoylacetate (62.3-68.4% e.e.)207. This may be due to the fact that the silyl ether could be produced not only by the hydrosilylation, but also by in situ transfer hydrogenation of the silyl enol ether (a mixture of E and Z isomers), which is formed in the first step of the reaction by dehydrogenative coupling of the enol with the hydrosilane. 

The reductive amination of carbonyl compounds can be regarded as a special case of C=N reduction. For this purpose, an aldehyde or ketone is in situ transferred into the corresponding imine and directly reduced to the respective amine. The imine is not isolated, and therefore, its workup and purification is avoided. 

Basu., B., Date, A.W. Int. J. Heat Mass Transfer, 33 (1990) Nr. 6, S.l 149 Haferkamp, H., Gerken, J., Stegemann, D., Reichert, Ch. In-situ Untersuchung des Hartstofftransports beim Laserstrahl-Dispergieren mittels Hochgeschwindigkeits-Radioskopie, Metall, Nr. 3/96... 

Studies of the liquid-solid interface can be divided into those that are perfonned ex situ and those perfomied in situ. In an ex situ experiment, a surface is first reacted in solution, and then removed from the solution and transferred into a UFIV spectrometer for measurement. There has recently been, however, much work aimed at interrogating the liquid-solid interface in situ, i.e. while chemistry is occurring rather than after the fact. 

Acetylene is also protected as propargyl alcohol (300)[2H], which is depro-tected by hydrolysis with a base, or oxidation with MnOi and alkaline hydrolysis. Sometimes, propargyl alcohols are isomerized to enals. Propargyl alcohol (300) reacts with 3-chloropyridazine (301) and EtiNH to give 3-diethylami-noindolizine (303) in one step via the enal 302[2I2]. Similarly, propargyl alcohol reacts with 2-halopyridines and secondary amines. 2-Methyl-3-butyn-2-ol (304) is another masked acetylene, and is unmasked by treatment with KOH or NaOH in butanol[205,206,213-2l5] or in situ with a phase-transfer cata-lyst[2l6]. 

Polymerisation casting involves mixing monomer or low molecular weight polymer with a polymerisation initiator, pouring the mix into the mould and allowing polymerisation to occur in situ. A variation is to impregnate fibres with initiated monomer or other low molecular weight material and polymerise to produce composite structures. The main problem is due to the heat of polymerisation. Unless heat transfer distances are kept short or unless the reaction is carried out very slowly it can easily get out of hand. 

The bond between the trifluoromethyl group and boron is difficult to form Preparation of trifluoromethyl aminohoranes was successfully achieved by transfer of trifluoromethyl group from reagent 2, which was prepared in situ [107] (equation 85)... 

Phase-transfer systems for generating fluorohalocarbenes from the corre spending haloforms are simple and effective with nucleophilic olefins [5J, 54 55, 56, 57, 58, 59] (Table 3 and equations 23 and 24), and the process was extended recently to difluorocarbene [60] Chlorofluorocarbene also can be generated from fluorotrichloromethane and utanium(O) produced in situ (T1CI4 + L1AIH4) Yields of gem-chlorofluorocyclopropanes range from excellent (85% for a. meth ylstyrene) to poor (12% for 1-hexene) [61]... 

Pd-C using transfer hydrogenation. A number of methods have been developed in which hydrogen is generated in situ. These include the use of cyclohexene (1-8 h, 80-90% yield)," cyclohexadiene (25°, 2 h, good yields)," HC02H, ammonium formate (MeOH, reflux, 91% yield), ... 

NaH, /7-MeOQH4CH2Br, DMF, —5°, 1 h, 65%. Other bases, such as BuLi, ° dimsyl potassium," and NaOH under phase-transfer conditions," have been used to introduce the MPM group. The use of (n-Bu)4N I for the in situ preparation of the very reactive p-methoxybenzyl iodide often improves the protection of hindered alcohols." In the following example, selectivity is probably achieved because of the increased acidity of the 2 -hydroxyl group ... 

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