Reactions of Cyclopropylcarbinyl Halides with (Trimethylstannyl)alkalis. Evidence that Kinetically Free Intermediates Need Not Be Involved in Cyclopropylcarbinyl to 3-Butenyl Rearrangements

Mikhail S. Alnajjar, Gary F. Smith, Henry G. Kuivila

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Studies on the reactions of cyclopropylcarbinyl bromide and iodide with trimethylstannyl anionoids have been made with emphasis on counterion, solvent, and addend (teri-butylamine and dicyclohexylphosphine) effects. Both halides yield cyclopropylcarbinyl- and 3-butenyltrimethylstannanes as major products. Depending upon reaction parameters much or all of the latter is shown to be formed by a mechanism or mechanisms which do not involve kinetically free radical or ionic intermediates. With cyclopropylcarbinyl bromide no electron transfer (ET) (free radical) component is observed in THF or in THF-containing 18-crown-6. However, in 20% THF-80% benzene a small extent of the ET mechanism is observed in the presence of DCPH. The iodide reacts in THF via SN2 (or equivalent) and halogen-metal exchange (HME) mechanisms leading to the formation of both methylcyclopropane and 1-butene in the presence of the traps, indicating that the cyclopropylcarbinyl anion can undergo rearrangement to the 3-butenyl anion in competition with other processes. In the presence of 18-crown-6 and DCPH a small ET component is observed with the iodide.

Original languageEnglish (US)
Pages (from-to)1271-1276
Number of pages6
JournalJournal of Organic Chemistry
Volume49
Issue number7
DOIs
StatePublished - Jan 1 1984

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Alkalies
Iodides
Bromides
Free Radicals
Anions
Electrons
Butylamines
Halogens
Benzene
Metals
18-crown-6

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

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title = "Reactions of Cyclopropylcarbinyl Halides with (Trimethylstannyl)alkalis. Evidence that Kinetically Free Intermediates Need Not Be Involved in Cyclopropylcarbinyl to 3-Butenyl Rearrangements",
abstract = "Studies on the reactions of cyclopropylcarbinyl bromide and iodide with trimethylstannyl anionoids have been made with emphasis on counterion, solvent, and addend (teri-butylamine and dicyclohexylphosphine) effects. Both halides yield cyclopropylcarbinyl- and 3-butenyltrimethylstannanes as major products. Depending upon reaction parameters much or all of the latter is shown to be formed by a mechanism or mechanisms which do not involve kinetically free radical or ionic intermediates. With cyclopropylcarbinyl bromide no electron transfer (ET) (free radical) component is observed in THF or in THF-containing 18-crown-6. However, in 20{\%} THF-80{\%} benzene a small extent of the ET mechanism is observed in the presence of DCPH. The iodide reacts in THF via SN2 (or equivalent) and halogen-metal exchange (HME) mechanisms leading to the formation of both methylcyclopropane and 1-butene in the presence of the traps, indicating that the cyclopropylcarbinyl anion can undergo rearrangement to the 3-butenyl anion in competition with other processes. In the presence of 18-crown-6 and DCPH a small ET component is observed with the iodide.",
author = "Alnajjar, {Mikhail S.} and Smith, {Gary F.} and Kuivila, {Henry G.}",
year = "1984",
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AU - Kuivila, Henry G.

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N2 - Studies on the reactions of cyclopropylcarbinyl bromide and iodide with trimethylstannyl anionoids have been made with emphasis on counterion, solvent, and addend (teri-butylamine and dicyclohexylphosphine) effects. Both halides yield cyclopropylcarbinyl- and 3-butenyltrimethylstannanes as major products. Depending upon reaction parameters much or all of the latter is shown to be formed by a mechanism or mechanisms which do not involve kinetically free radical or ionic intermediates. With cyclopropylcarbinyl bromide no electron transfer (ET) (free radical) component is observed in THF or in THF-containing 18-crown-6. However, in 20% THF-80% benzene a small extent of the ET mechanism is observed in the presence of DCPH. The iodide reacts in THF via SN2 (or equivalent) and halogen-metal exchange (HME) mechanisms leading to the formation of both methylcyclopropane and 1-butene in the presence of the traps, indicating that the cyclopropylcarbinyl anion can undergo rearrangement to the 3-butenyl anion in competition with other processes. In the presence of 18-crown-6 and DCPH a small ET component is observed with the iodide.

AB - Studies on the reactions of cyclopropylcarbinyl bromide and iodide with trimethylstannyl anionoids have been made with emphasis on counterion, solvent, and addend (teri-butylamine and dicyclohexylphosphine) effects. Both halides yield cyclopropylcarbinyl- and 3-butenyltrimethylstannanes as major products. Depending upon reaction parameters much or all of the latter is shown to be formed by a mechanism or mechanisms which do not involve kinetically free radical or ionic intermediates. With cyclopropylcarbinyl bromide no electron transfer (ET) (free radical) component is observed in THF or in THF-containing 18-crown-6. However, in 20% THF-80% benzene a small extent of the ET mechanism is observed in the presence of DCPH. The iodide reacts in THF via SN2 (or equivalent) and halogen-metal exchange (HME) mechanisms leading to the formation of both methylcyclopropane and 1-butene in the presence of the traps, indicating that the cyclopropylcarbinyl anion can undergo rearrangement to the 3-butenyl anion in competition with other processes. In the presence of 18-crown-6 and DCPH a small ET component is observed with the iodide.

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