Aiichiro Nagaki

Friedel-Crafts reactions of aromatic and heteroaromatic compounds with an N-acyliminium ion pool were studied. The reaction of 1,3,5-trimethylbenzene in a batch reactor gave rise to the selective formation of a monoalkylation product (69%). Presumably, the second alkylation is slower than the first alkylation because of the protonation of the monoalkylation product that decreases its reactivity. The reaction of 1,3,5-trimethoxybenzene, however, gave rise to the formation of both monoalkylation (

The "cation pool" of an N-acyliminium ion was found to serve as an effective initiator of cationic polymerization of vinyl ethers in a microsystem consisting of two micromixers and a microtube reactor. The polymerization led to very narrow molecular weight distribution (Mw/Mn = 1.14). The molecular weight (Mn) increased linearly with an increase in the amount of the monomer. The carbocationic polymer end was effectively trapped by allyltrimethylsilane. The present observations illustrate the pot

Going with the flow: The use of palladium catalysts bearing a carbene ligand resulted in a faster Murahashi coupling, and enabled its integration with the Br–Li exchange of ArBr with BuLi in a microreactor (see picture). This system allows the cross-coupling of two different aryl bromides within a minute without necessitating low temperatures (−78°C). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edite

Go with the flow: An effective method for the generation and reaction of aryllithium compounds bearing an alkoxycarbonyl group is developed using microflow systems with very short residence times together with fast mixing and efficient temperature control. A wide range of alkoxycarbonyl groups including ethoxycarbonyl and methoxycarbonyl groups are tolerant of the microflow conditions. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/

Be quick or take your time, depending on your goal: A microflow method for the generation and transformation of o-, m-, and p-nitro-substituted aryl lithium compounds enabled the selective use of either the kinetically or the thermodynamically preferred intermediate. In the example pictured, a residence time of 0.06 s at −48 °C led to the formation of 1, whereas 2 was obtained exclusively when the residence time was extended to 63 s. Detailed facts of importance to specialist readers are publish

A flow microreactor method for three-component coupling of benzyne was developed based on flash chemistry. o-Bromophenyllithium generated from 1-bromo-2-iodobenzene and a functionalized aryllithium generated from the corresponding aryl halide were mixed at -70 °C. In the subsequent reactor o-bromophenyllithium is decomposed to generate benzyne without affecting the functionalized aryllithium at -30 °C, and carbolithiation of benzyne with the aryllithium took place spontaneously. The resulting fu

We developed a microflow method for the generation and reactions of aryllithiums bearing a cyano group, including o-lithiobenzonitrile, m-lithiobenzonitrile and p-lithiobenzonitrile. The method was effective at much higher temperatures than are required for conventional macrobatch reactions, by virtue of rapid mixing, short residence time, and efficient temperature control. In addition, reactions of o-lithiobenzonitrile with carbonyl compounds followed by trapping of the resulting lithium alkoxi

Deprotonation of epoxides followed by trapping with electrophiles was carried out using microflow systems with varying temperature and residence time. Time-dependence of the yields of products provides a deeper insight into chemical and configurational stabilities of oxiranyllithiums. With the thus-obtained information, reactions of oxiranyllithiums with various electrophiles were successfully carried out without decomposition and isomerization.

It′s all about the timing: Precise control of the residence time (tRx; see picture) of reactive intermediates in flow microreactors enables the reaction pathway of lithiated 1,2-dichloroethene to be switched to produce either alkenes or alkynes. This method also allows versatile syntheses of asymmetric disubstituted dichloroalkenes and alkynes. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or ty

Selective monolithiation of dibromobiaryls, such as 2,2'-dibromobiphenyl, 4,4'-dibromobiphenyl, 2,7-dibromo-9,9-dioctylfluorene, 2,2'-dibromo-1,1'-binaphthyl, and 5,5'-dibromo-2,2'-bithiophene, with 1 equiv of n-butyllithium followed by the reaction with electrophiles was achieved using a microflow system by virtue of fast micromixing and precise temperature control. Sequential introduction of two different electrophiles based on this method was also achieved using a microflow system composed of

A micro flow system consisting of micromixers and microtube reactors provides an effective method for the introduction of two electrophiles onto p-, m-, and o-dibromobenzenes. The Br-Li exchange reaction of p-dibromobenzene with nBuLi can be conducted by using the micro flow system at 20 degrees C, although much lower temperatures (< -48 degrees C) are needed for a batch reaction. The resulting p-bromophenyllithium was allowed to react with an electrophile in the micro flow system at 20 degrees

Flash chemistry using flow microreactors enables highly chemoselective reactions of difunctional electrophiles with functionalized aryllithium compounds by virtue of extremely fast micromixing. The approach serves as a powerful method for protecting-group-free synthesis using organolithium compounds and opens a new possibility in the synthesis of polyfunctional organic molecules.

A flow microreactor system consisting of micromixers and microtube reactors provides an effective tool for the generation and reactions of aryllithiums bearing an alkoxycarbonyl group at para-, meta-, and ortho-positions. Alkyl p- and m-lithiobenzoates were generated by the I/Li exchange reaction with PhLi. The Br/Li exchange reactions with sBuLi were unsuccessful. Subsequent reactions of the resulting aryllithiums with electrophiles gave the desired products in good yields. On the other hand, a

Anionic polymerization of styrene using sec-BuLi as an initiator was conducted in a microflow system. A high level of molecular-weight distribution control was achieved under easily accessible conditions, such as at 0 °C (Mw/Mn = 1.08) and 24 °C (Mw/Mn = 1.10). The polymerization of styrene derivatives having silyl, methoxy, silyloxy, alkynyl, and alkylthio groups on the benzene ring also took place in a highly controlled manner using sec-BuLi as an initiator. The end functionalization using chl

Carboxylation of short-lived organolithiums bearing electrophilic functional groups such as nitro, cyano, and alkoxycarbonyl groups with CO2 to give carboxylic acids and active esters was accomplished in a flow microreactor system. The successful reactions indicate that gas/liquid mass transfer and the subsequent chemical reaction with CO2 are extremely fast.