Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor

T.R. Kelly, XL Cai, F. Damkaci, S.B. Panicker, B. Tu, S.M. Bushell, I. Cornella, Matthew Piggott, R. Salives, M. Cavero, YJ Zhao, S. Jasmin

Research output: Contribution to journalArticle

114 Citations (Scopus)

Abstract

Building on prototype 1, which achieves 120° of phosgene-powered unidirectional rotation to rotamer 6 (see Figure 5 in the full article), 7 was designed to accomplish repeated unidirectional rotation (see Scheme 7). Compound 7 contains an amino group on each blade of the triptycene and a 4-(dimethylamino)pyridine (DMAP) unit to selectively deliver phosgene (or its equivalent) to the amine in the “firing position”. The synthesis of 7 is described: the key constructive steps are a benzyne addition to an anthracene to generate the triptycene, a stilbene photocyclization to construct the helicene, and a Stille coupling to incorporate the DMAP unit. The DMAP unit was shown to regioselectively relay 1,1‘-carbonyldiimidazole (but not phosgene) to the proximal amino group, as designed, but rotation of the triptycene does not occur. Extensive attempts to troubleshoot the problem led to the conclusion that the requisite intramolecular urethane formation, as demonstrated in the prototype (1 → 4), does not occur with 7 (to give 85) or 97 (to give 100). We speculate that either (i) hydrogen bonding between the hydroxypropyl group and functionality present in 7 but absent from 1 or (ii) a Bürgi−Dunitz (or similar) interaction involving the DMAP (see 106) prevents achievement of a conformation conducive to intramolecular urethane formation.
Original languageEnglish
Pages (from-to)376-386
JournalJournal of American Chemical Society
Volume129
Issue number2
DOIs
Publication statusPublished - 2007

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Phosgene
Pyridine
Urethane
Stilbenes
Anthracene
Hydrogen Bonding
Amines
Conformations
Hydrogen bonds
pyridine
4-(dimethylamino)pyridine
triptycene

Cite this

Kelly, T. R., Cai, XL., Damkaci, F., Panicker, S. B., Tu, B., Bushell, S. M., ... Jasmin, S. (2007). Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor. Journal of American Chemical Society, 129(2), 376-386. https://doi.org/10.1021/ja066044a
Kelly, T.R. ; Cai, XL ; Damkaci, F. ; Panicker, S.B. ; Tu, B. ; Bushell, S.M. ; Cornella, I. ; Piggott, Matthew ; Salives, R. ; Cavero, M. ; Zhao, YJ ; Jasmin, S. / Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor. In: Journal of American Chemical Society. 2007 ; Vol. 129, No. 2. pp. 376-386.
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abstract = "Building on prototype 1, which achieves 120° of phosgene-powered unidirectional rotation to rotamer 6 (see Figure 5 in the full article), 7 was designed to accomplish repeated unidirectional rotation (see Scheme 7). Compound 7 contains an amino group on each blade of the triptycene and a 4-(dimethylamino)pyridine (DMAP) unit to selectively deliver phosgene (or its equivalent) to the amine in the “firing position”. The synthesis of 7 is described: the key constructive steps are a benzyne addition to an anthracene to generate the triptycene, a stilbene photocyclization to construct the helicene, and a Stille coupling to incorporate the DMAP unit. The DMAP unit was shown to regioselectively relay 1,1‘-carbonyldiimidazole (but not phosgene) to the proximal amino group, as designed, but rotation of the triptycene does not occur. Extensive attempts to troubleshoot the problem led to the conclusion that the requisite intramolecular urethane formation, as demonstrated in the prototype (1 → 4), does not occur with 7 (to give 85) or 97 (to give 100). We speculate that either (i) hydrogen bonding between the hydroxypropyl group and functionality present in 7 but absent from 1 or (ii) a B{\"u}rgi−Dunitz (or similar) interaction involving the DMAP (see 106) prevents achievement of a conformation conducive to intramolecular urethane formation.",
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Kelly, TR, Cai, XL, Damkaci, F, Panicker, SB, Tu, B, Bushell, SM, Cornella, I, Piggott, M, Salives, R, Cavero, M, Zhao, YJ & Jasmin, S 2007, 'Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor' Journal of American Chemical Society, vol. 129, no. 2, pp. 376-386. https://doi.org/10.1021/ja066044a

Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor. / Kelly, T.R.; Cai, XL; Damkaci, F.; Panicker, S.B.; Tu, B.; Bushell, S.M.; Cornella, I.; Piggott, Matthew; Salives, R.; Cavero, M.; Zhao, YJ; Jasmin, S.

In: Journal of American Chemical Society, Vol. 129, No. 2, 2007, p. 376-386.

Research output: Contribution to journalArticle

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T1 - Progress toward a Rationally Designed, Chemically Powered Rotary Molecular Motor

AU - Kelly, T.R.

AU - Cai, XL

AU - Damkaci, F.

AU - Panicker, S.B.

AU - Tu, B.

AU - Bushell, S.M.

AU - Cornella, I.

AU - Piggott, Matthew

AU - Salives, R.

AU - Cavero, M.

AU - Zhao, YJ

AU - Jasmin, S.

PY - 2007

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N2 - Building on prototype 1, which achieves 120° of phosgene-powered unidirectional rotation to rotamer 6 (see Figure 5 in the full article), 7 was designed to accomplish repeated unidirectional rotation (see Scheme 7). Compound 7 contains an amino group on each blade of the triptycene and a 4-(dimethylamino)pyridine (DMAP) unit to selectively deliver phosgene (or its equivalent) to the amine in the “firing position”. The synthesis of 7 is described: the key constructive steps are a benzyne addition to an anthracene to generate the triptycene, a stilbene photocyclization to construct the helicene, and a Stille coupling to incorporate the DMAP unit. The DMAP unit was shown to regioselectively relay 1,1‘-carbonyldiimidazole (but not phosgene) to the proximal amino group, as designed, but rotation of the triptycene does not occur. Extensive attempts to troubleshoot the problem led to the conclusion that the requisite intramolecular urethane formation, as demonstrated in the prototype (1 → 4), does not occur with 7 (to give 85) or 97 (to give 100). We speculate that either (i) hydrogen bonding between the hydroxypropyl group and functionality present in 7 but absent from 1 or (ii) a Bürgi−Dunitz (or similar) interaction involving the DMAP (see 106) prevents achievement of a conformation conducive to intramolecular urethane formation.

AB - Building on prototype 1, which achieves 120° of phosgene-powered unidirectional rotation to rotamer 6 (see Figure 5 in the full article), 7 was designed to accomplish repeated unidirectional rotation (see Scheme 7). Compound 7 contains an amino group on each blade of the triptycene and a 4-(dimethylamino)pyridine (DMAP) unit to selectively deliver phosgene (or its equivalent) to the amine in the “firing position”. The synthesis of 7 is described: the key constructive steps are a benzyne addition to an anthracene to generate the triptycene, a stilbene photocyclization to construct the helicene, and a Stille coupling to incorporate the DMAP unit. The DMAP unit was shown to regioselectively relay 1,1‘-carbonyldiimidazole (but not phosgene) to the proximal amino group, as designed, but rotation of the triptycene does not occur. Extensive attempts to troubleshoot the problem led to the conclusion that the requisite intramolecular urethane formation, as demonstrated in the prototype (1 → 4), does not occur with 7 (to give 85) or 97 (to give 100). We speculate that either (i) hydrogen bonding between the hydroxypropyl group and functionality present in 7 but absent from 1 or (ii) a Bürgi−Dunitz (or similar) interaction involving the DMAP (see 106) prevents achievement of a conformation conducive to intramolecular urethane formation.

U2 - 10.1021/ja066044a

DO - 10.1021/ja066044a

M3 - Article

VL - 129

SP - 376

EP - 386

JO - Journal of the Amercian Chemical Society

JF - Journal of the Amercian Chemical Society

SN - 0002-7863

IS - 2

ER -