Using hydrogen bonding to control carbamate C-N rotamer equilibria

Alexei L. Moraczewski; Laura A. Banaszynski; Aaron M. From; Courtney E. White; Bradley D. Smith

doi:10.1021/jo980644d

Using hydrogen bonding to control carbamate C-N rotamer equilibria

Alexei L. Moraczewski, Laura A. Banaszynski, Aaron M. From, Courtney E. White, Bradley D. Smith

Research output: Contribution to journal › Article › peer-review

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Abstract

In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effect on the syn/anti ratio for 3. Conversely, the hydrogen bond donor-acceptor-donor triad in 2,6-bis(octylamido)pyridine, 1, strongly stabilizes the syn rotamer of 3, but has no effect on the syn/anti ratio for 4. The K& for syn-3:l is 103-104 times higher than the K1 for anti-3:l. This implies that the alkoxy oxygen in anti-3 is a much poorer hydrogen bond acceptor than the carbonyl oxygen in syn-3, most likely because of a combination of steric and electrostatic factors.

Original language	English (US)
Pages (from-to)	7258-7262
Number of pages	5
Journal	Journal of Organic Chemistry
Volume	63
Issue number	21
DOIs	https://doi.org/10.1021/jo980644d
State	Published - Oct 16 1998

ASJC Scopus subject areas

Organic Chemistry

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title = "Using hydrogen bonding to control carbamate C-N rotamer equilibria",

abstract = "In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effect on the syn/anti ratio for 3. Conversely, the hydrogen bond donor-acceptor-donor triad in 2,6-bis(octylamido)pyridine, 1, strongly stabilizes the syn rotamer of 3, but has no effect on the syn/anti ratio for 4. The K& for syn-3:l is 103-104 times higher than the K1 for anti-3:l. This implies that the alkoxy oxygen in anti-3 is a much poorer hydrogen bond acceptor than the carbonyl oxygen in syn-3, most likely because of a combination of steric and electrostatic factors.",

author = "Moraczewski, {Alexei L.} and Banaszynski, {Laura A.} and From, {Aaron M.} and White, {Courtney E.} and Smith, {Bradley D.}",

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T1 - Using hydrogen bonding to control carbamate C-N rotamer equilibria

AU - Moraczewski, Alexei L.

AU - Banaszynski, Laura A.

AU - From, Aaron M.

AU - White, Courtney E.

AU - Smith, Bradley D.

PY - 1998/10/16

Y1 - 1998/10/16

N2 - In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effect on the syn/anti ratio for 3. Conversely, the hydrogen bond donor-acceptor-donor triad in 2,6-bis(octylamido)pyridine, 1, strongly stabilizes the syn rotamer of 3, but has no effect on the syn/anti ratio for 4. The K& for syn-3:l is 103-104 times higher than the K1 for anti-3:l. This implies that the alkoxy oxygen in anti-3 is a much poorer hydrogen bond acceptor than the carbonyl oxygen in syn-3, most likely because of a combination of steric and electrostatic factors.

AB - In chloroform solution, the syn/anti rotamer ratios for AT-(2-pyridyl)carbamates, 3, and JV-phenylcarbamates, 4, are close to 0.05. Addition of the double hydrogen bonding acetic acid moderately stabilizes the syn rotamer of 4, but has no measurable effect on the syn/anti ratio for 3. Conversely, the hydrogen bond donor-acceptor-donor triad in 2,6-bis(octylamido)pyridine, 1, strongly stabilizes the syn rotamer of 3, but has no effect on the syn/anti ratio for 4. The K& for syn-3:l is 103-104 times higher than the K1 for anti-3:l. This implies that the alkoxy oxygen in anti-3 is a much poorer hydrogen bond acceptor than the carbonyl oxygen in syn-3, most likely because of a combination of steric and electrostatic factors.

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Using hydrogen bonding to control carbamate C-N rotamer equilibria

Abstract

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