The reaction of 6-chlorohex-1-ene 1 with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5% molar) in THF at −78°C gives the corresponding organolithium intermediate 2, which by reaction with different electrophiles affords, after hydrolysis with diluted hydrochloric acid, the expected products 3. The same reaction performed at −30°C gives cyclopentyl derivatives 5, probably by cyclisation of the open-chain intermediate 2 to give the cyclic organolithium compound 4. When the double bond in the starting material contains an alkyl substituent, for instance compounds 6 and 9, the corresponding cyclisation is inhibited, so the corresponding acyclic products 8 and 11 are respectively, obtained. However, when the substituent at the same positions is a phenyl group, like in starting materials 12 and 15, the cyclised products 14 and 17 were respectively, isolated. In the case of the secondary starting chlorinated material 18, the reaction can be directed to both, the acyclic products 20 or the cyclic ones 22, working at −78 or −30°C, respectively, as it happens in the case of the unsubstituted chlorinated material 1. For the tertiary chloro derivative 23, only the cyclic compound 27 could be isolated at −30°C due to the great instability of the corresponding tertiary organolithium intermediate 24, which undergoes a proton abstraction even at −78°C. From allyl 2-chlorophenyl ether 28 or N,N-diallyl-2-chloroaniline 32, only the corresponding cyclic compounds 31 and 33, respectively, are isolated either at −78 or at −30°C. In all cases a carbanionic cyclisation, better than a radical one, is postulated to occur as mechanistic pathway.

The reaction of 6-chloro-1-hexene 1 with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5% molar) in THF at −78°C gives the corresponding organolithium intermediate 2, which by reaction with different electrophiles [ButCHO, PhCHO, Et2CO, (CH2)5CO, PhCOMe] affords, after hydrolysis with water, the expected products 3. The same reaction performed at −30°C gives cyclopentyl derivatives 5, probably by cyclisation of the open-chain intermediate 2 to give the cyclic organolithium compound 4. For the tertiary derivative 6, only the cyclic compound 10 could be isolated at −30°C due to the great instability of the corresponding tertiary organolithium intermediate 7, which undergoes a proton abstraction even at −78°C. From allyl 2-chloro-phenyl ether 11 only the corresponding cyclic compound 14 was isolated either at −78°C or at −30°C. In all cases a carbanionic cyclisation, better than a radical one, is postulated to occur.

The reaction of 2-(chlorophenyl)-1,3-dioxolanes 1 with an excess of lithium powder and a catalytic amount of naphthalene (5 mol %) in the presence of different carbonyl compounds [tBuCHO, Et2CO, (CH2)5CO, PhCOMe] as electrophiles (Barbier-type conditions) in THF at −78°C leads, after hydrolysis with water at the same temperature, to the expected products 3, the corresponding intermediates involved being formyl- or acetyl-phenyl anion equivalents.

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The reaction of chlorinated benzyl chlorides (1) with an excess of lithium powder and a catalytic amount of DTBB (4 mol %) in the presence of different electrophiles [PriCHO, ButCHO, Et2CO, (CH2)5CO, PhCOMe, Me3SiCl] in THF at −50°C followed by hydrolysis with water leads to the corresponding compounds 2. When the same DTBB-catalysed lithiation is applied to several chlorinated benzylic alcohols or mercaptans (4 or 5) it is necessary to deprotonate the starting material with BunLi; treatment of the resulting anions or amine 6 as above, but at −78°C, leads to the expected reaction products 8, after reaction with different electrophiles [PriCHO, ButCHO, Et2CO, (CH2)5CO, PhCOMe, Me3SiCl] and final hydrolysis with water.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The reaction of different 3-chlorinated allyl amines 1a,b or phenylether 1c with an excess of lithium powder, a catalytic amount of DTBB (5 mol %) and an electrophile [PriCHO, ButCHO, Et2CO, (CH2)5CO] in THF at −78°C gives, after hydrolysis with water, the expected ZE mixture of the corresponding products 2. The corresponding two-step process at temperatures ranging between −30 and −40°C [electrophiles: PriCHO, ButCHO, (CH2)5CO] yields propargylic derivatives 3. A mechanistic explanation for this behaviour is given.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The reaction of chlorinated acetylenic ether or amines 1 with lithium and a catalytic amount of DTBB (5%), in the presence of different electrophiles [PriCHO, BulCHO, PhCHO, Me2CO, (CH2)5CO, Me3SiCl] in THF at −78 or −105°C leads, after hydrolysis with water, to the corresponding products 2. The same process applied to the previously deprotonated chloroalcohol 4a or the secondary amine 4b can be carried out in a two-step reaction giving the expected products 6 by using several electrophiles [PriCHO, ButCHO, PhCHO, Me2CO, (CH2)5CO, Me3SiCl] at −78°C.

The reaction of 1,2-, 1,3- and 1,4-di(chloromethyl)benzenes (1a-c) and different electrophiles [PriCHO, ButCHO, PhCHO, (CH2)5CO, PhCOMe, Me3SiCl] with an excess of lithium powder and a catalytic amount of DTBB (4 mol%) in THF at 0°C leads, after hydrolysis with water, to the expected dioles or disilylated compounds 2aa-cf.

The reaction of N,N-disubstituted (E)-4-amino-1-chloro-2-butenes 1 with an excess of lithium and a catalytic amount of DTBB in the presence of an electrophile [E+ = ButCHO, PhCHO, Me2CO, (CH2)5CO, (c-C3H5)2CO, Me3SiCl] in THF at −78°C leads, after hydrolysis with water, to the expected mixture of 1,2- and 1,4- disubstituted compounds (2 and 3, respectively), which could be easily separated by flash chromatography. When the reaction was applied either to the corresponding (Z)-starting materials or to (Z)- or (E)-oxygen or sulfur containing chlorinated 2-butenes the yields are poorer than for nitrogenated precursors.

The reaction of ketalised 1-chlorobutane-3,4-diol 1a,b with lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 4 mol %) in the presence of an electrophile [PriCHO, ButCHO, PhCHO, PrnCOMe, (CH2)5CO] at −78°C in THF (Method A: Barbier-type conditions) leads, after hydrolysis, to the formation of the corresponding ketalised reaction products 2aa-bf. Alternatively, the reaction can be carried out in a two-step process (Method B), which implies first a DTBB-catalysed lithiation folowed by reaction with an electrophile [Me3SiCl, PriCHO, ButCHO, PhCHO, Me2CO, Et2CO, PrnCOMe, (CH2)5CO, PhCOMe] both steps being performed at −78°C. When the starting materials are chiral, this methodology allows the preparation of chiral protected di or triols in a nondiastereoselective manner.

The reaction of 2,3-dichloropropene (1) and different carbonyl compounds (2) with an excess of lithium powder (1:7 molar ratio) in the presence of a catalytic amount of DTBB (5 mol %) in THF at 0 degrees C leads,after hydrolysis with water, to the corresponding methylenic 1,4-diols 3 in a Barbier-type process. The cyclisation of diols 3 under acidic conditions (hydrochloric or phosphoric acid) yields the corresponding substituted methylenic tetrahydrofurans 4. Finally, 2,3-dichloropropene (1) is converted into the corresponding allylic chloroamines 5 and then submitted to the tandem naphthalene-catalysed lithiation-dB reaction with different electrophiles affording the corresponding functionalised amines 7. The last process fails for oxygen- or sulfur-containing chloroallylic materials 8.