79239-04-6

Upstream product

• 123315-30-0 ethyl 2-trimethylsilylmethylbutyrate 
• 123315-24-2 ethyl 2-butyroate 
• 128742-43-8 1,1-diphenylspiro[2.2]pentane 
• 79238-99-6 1,1-diphenyl-2-trimethylsilylmethylbutan-1-ol 
• 66129-95-1 (2-methylbut-1-ene-1,1-diyl)dibenzene 

Relevant academic research and scientific papers

Polylithiumorganic compounds. Part 29: C,C Bond cleavage of phenyl substituted and strained carbocycles using lithium metal

The reaction of phenyl substituted cyclopropanes phenylcyclopropane and 1,1-diphenylcyclopropane, phenyl substituted bicyclobutanes 1- phenylbicyclobutane, 1-methyl-3-phenylbicyclobutane, 1-methyl-2,2- diphenylbicyclobutane, as well as phenyl substituted spiropentanes phenylspiropentane and 1,1-diphenylspiropentane with lithium metal or lithium di-t-butylbiphenyl (LiDBB) was investigated. Under suitable reaction conditions and choice of solvent in all cases cleavage of the single bond next to the activating phenyl group was observed. The dilithiumorganic compounds thus obtained are sufficiently stable and can be trapped with electrophiles. Lithium hydride elimination is observed as follow-up reaction only in a few cases. The corresponding anions of the strained ring systems 1-lithio-2,2- diphenylcyclopropane, 1-lithio-3-phenylbicyclobutane, 1-lithio-3-methyl-2,2- diphenylbicyclobutane, and 1-lithio-4-phenylspiropentane, which can be obtained by lithium bromine exchange or by metalation of the unsubstituted carbocycle, do not show any cleavage upon reaction with lithium metal. The reaction of phenyl substituted cyclopropanes, bicyclobutanes as well as spiropentanes with lithium metal with formation of highly reactive dilithiumorganic compounds was investigated. In all cases cleavage of the bond next to the phenyl substituent(s) was observed.

Carbonium Ion Rearrangements Controlled by the Presence of a Silyl Group

γ-Silyl tertiary alcohols rearrange in protic acid with 1,2-shift of hydride, phenyl, or alkyl groups, and loss of the silyl group to give alkenes.The placing of the silyl group thus controls the carbonium ion rearrangement in a preparatively useful way.Methoxycarbonyl groups do not migrate; instead, cyclopropanes are formed, except when the conformation suitable for cyclopropane formation is unattainable.When the alkene product is 2,2-disubstituted, it can be reprotonated under the reaction conditions and does not therefore always survive.This can be avoided by carrying out the reaction using a Lewis acid on the silyl ether.The starting γ-silyl alcohols are prepared by a variety of versatile methods.

Radical ions in photochemistry. 18. The photosensitized (electron transfer) tautomerization of alkenes; the 1,1-diphenyl alkene system

The photosensitized (electron transfer) irradiation of several conjugated 1,1-diphenyl alkenes, in acetonitrile with 1,4-dicyanobenzene or 1-cyanonaphthalene as electron accepting sensitizer and 2,6-lutidine as base, leads essentially quantitatively to tautomerization to the less stable unconjugated isomer(s).The proposed mechanism for this reaction involves formation of the alkene radical cation and sensitizer radical anion followed by deprotonation of the radical cation, reduction of the resulting radical to the ambident anion by back electron transfer from the radical anion, and reprotonation.There are several steps in this mechanism that could control the ratio of isomers.Evidence is provided that, at least in some cases, it is the relative rate of deprotonation from the isomeric radical cations that is the determining factor.This rate is influenced by the conformation of the radical cation; the carbon-hydrogen bond involved in the deprotonation step must overlap with the singly occupied molecular orbital.

CARBONIUM ION REARRANGEMENTS CONTROLLED BY THE PRESENCE OF A SILYL GROUP

Tertiary alcohols with a γ-silyl group (3) generally undergo a simple carbonium ion rearrangement in acid giving a single alkene product (4) with loss of the silyl group.

Some uses of silicon compounds in organic synthesis

1.The amount of γ-phenylthioalkylation of silyl dienol ethers is increased when the triphenylsilyl ether is used in place of the trimethylsilyl ether.Phenylthiomethylation is the least γ-selective carbon electrophile of several tried so far. 2.The acid-catalysed reactions of a range of γ-silyl tertiary alcohols cleanly give rearrangement, in which the silyl group controls the outcome.The reactions are similar in several respects to the rearrangements of the corresponding pinacols, except that the silicon controlled reactions are usually cleaner and give higher yields.The reaction is particularly useful for setting up quaternary carbon atoms.