“…The lithium dehalogenation method was used in the synthesis 134 of 1-deuterio- and 1,3-dideuteriobicyclo[1.1.1]pentane ( 21 and 22 , 95% and 92% isotopic purity, respectively), starting from the properly labeled dibromides 147a . Electrochemical , cyclization of the dibromide 147a produced some bicyclo[1.1.1]pentane, as well as typical 1 side products such as 1,4-pentadiene, methylcyclobutane, and 1-pentene. 4 …”
ChemInform 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 lithium dehalogenation method was used in the synthesis 134 of 1-deuterio- and 1,3-dideuteriobicyclo[1.1.1]pentane ( 21 and 22 , 95% and 92% isotopic purity, respectively), starting from the properly labeled dibromides 147a . Electrochemical , cyclization of the dibromide 147a produced some bicyclo[1.1.1]pentane, as well as typical 1 side products such as 1,4-pentadiene, methylcyclobutane, and 1-pentene. 4 …”
ChemInform 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.
“…In the first step for the reduction of 1,4-pentadiene, an electron can add to either double bond to give a radical-anion, with the electron having a tendency to reside preferentially on a terminal methylene carbon (-CHzCHCH2CH=CH~); using the computer program MOPAC (Version 6.00) which uses the AM1 Hamiltonian, we calculated that one-electron reduction of 1,4-pentadiene results in an electron density of -0.43 on the terminal methylene carbon, -0.26 on the methine carbon, and -0.02 on the internal methylene carbon. Protonation can then occur at the terminal methylene carbon to yield a neutral radical (CH3CHCH2CH=CH2) which is further reduced to a secondary carbanion (reaction [1][2][3][4][5][6][7][8][9][10][11][12][13][14]; this secondary carbanion can be protonated to give 1-pentene (reaction [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] or can rearrange (reaction 1-15) before being protonated to form cis-or trans-2-pentene.…”
Studies of the electrochemical reduction of 1,5-dibromo-, 1,5-diiodo-, 1-bromo-5-chloro-, and 1-ch]oro-5-iodopentane at carbon electrodes in dimethylformamide containing tetramethylammonium perchlorate have been carried out with cyclic voltammetry and controlled-potential electrolysis. Cyclopentane, arising from the intramolecular cyclization of an electrogenerated 5-halopent-l-yl carbanion, is a significant electrolysis product. Moreover, depending on the identity of the 1,5-dihalopentane and the presence or absence of a proton source, one can obtain substantial yields of n-pentane, 1-pentene, 1-chloropentane, and 1,10-dichlorodecane as well as smaller amounts of cis-and trans-2-pentene, 5-chloro-1-pentene, 1,4-pentadiene, n-decane, 1-decene, n-pentadecane, 1-pentadecene, and n-eicosane. Experiments involving the use of several different deuterium ion or atom donors have been employed to determine the pathways by which these products are formed. In addition, we offer some comparisons concerning the electrochemical behavior of 1,3-dihalopropanes, 1,4-dihalobutanes, and 1,5-diha]opentanes at carbon cathodes.Only a limited amount of research concerning the electrochemistry of 1,5-dihalopentanes has been published, all of which pertains to the electrochemical reduction of 1,5-dibromopentane at mercury cathodes. 1-~ In a polarographic study of the reduction of 1,5-dibromopentane in dimethylformamide containing tetramethylammonium bromide and 5% water, Z~vada et al. 1 concluded that the starting material is reduced in a pair of two-electron steps which cannot be resolved into discrete waves. Rift 2'3 investigated the electrolytic reduction of 1,5-dibromopentane at a mercury pool in dimethylformamide containing tetra-n-butylammonium perehlorate and postulated that n-pentane is produced through a carbanion mechanism. However, different results were reported by Casanova and Rogers, ~ who found that controlled-potential electrolysis of 1,5-dibromopentane at mercury in dimethylformamide containing various tetraalkylammonium salts afforded a dialkylmercury species (CsHIoHgC~HI0) in high yield, whereas constant-current electrolysis of the same starting material gave only n-pentane. Avaca et al. ~ examined the electrochemical behavior of 1,5-dibromopentane in dimethyliormamide or acetonitrile containing various tetraalkylammonium salts at a mercury cathode and observed that controlled-potential eleetrolyses yielded mercury-containing solids with the general formula (C~HIoHg)~.In this paper we discuss the electrochemical reductions of 1,5-dibromo-, 1,5-diiodo-, l-bromo-5-ehloro-, and lchloro-5-iodopentane at carbon cathodes in dimethylformamide containing tetramethylammonium perehlorate; the electrochemistry of the last three 1,5-dihalopentanes has not been described previously. In performing this work, we have avoided the possible formation of organomercury compounds by not using mercury cathodes. We report for the first time the occurrence of electroreduetive intramolecular eyclization of each of the four 1,5-dihalopenfanes ...
“…Indeed, it was later demonstrated that electrochemical reductive cyclization 16 or complexation of zinc species with the tetrasodium salt of EDTA resulted in the formation of unrearranged products, such as spiropentane and spirohexane 15,17 . However, it was found that the use of other reducing agents, such as alkali metals or alkyllithiums (with gegen cations that do not have Lewis acid properties), still resulted in the formation of rearranged products, especially in nonpolar solvents 18 .…”
Section: A Reductive Dehalogenation Of Gem-(dihalomethyl)cycloalkanesmentioning
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