TY - JOUR
T1 - Quantification of Catalytic Activity for Electrostatically Enhanced Thioureas via Reaction Kinetics and UV-vis Spectroscopic Measurement
AU - Fan, Yang
AU - Payne, Curtis
AU - Kass, Steven R.
N1 - Publisher Copyright:
Copyright © 2018 American Chemical Society.
PY - 2018/9/21
Y1 - 2018/9/21
N2 - Charged thiourea derivatives containing one and two methylated or octylated pyridinium ion centers and a tetraarylborate or triflate counteranion are reported. These novel catalysts are much more active in the Friedel-Crafts reactions of trans-β-nitroalkenes with N-methylindoles than the privileged N,N′-bis(3,5-bis(trifluoromethyl)phenyl)thiourea (i.e., Schreiner's thiourea) by up to 2-3 orders of magnitude. A previously reported UV-vis spectroscopic method by Kozlowski et al. was exploited to rationalize their reactivity order along with noncharged analogues. These results offer a new design strategy for organocatalysts by introducing positively charged centers without adding additional N-H, O-H, or S-H hydrogen bond donor sites.
AB - Charged thiourea derivatives containing one and two methylated or octylated pyridinium ion centers and a tetraarylborate or triflate counteranion are reported. These novel catalysts are much more active in the Friedel-Crafts reactions of trans-β-nitroalkenes with N-methylindoles than the privileged N,N′-bis(3,5-bis(trifluoromethyl)phenyl)thiourea (i.e., Schreiner's thiourea) by up to 2-3 orders of magnitude. A previously reported UV-vis spectroscopic method by Kozlowski et al. was exploited to rationalize their reactivity order along with noncharged analogues. These results offer a new design strategy for organocatalysts by introducing positively charged centers without adding additional N-H, O-H, or S-H hydrogen bond donor sites.
UR - http://www.scopus.com/inward/record.url?scp=85050361079&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050361079&partnerID=8YFLogxK
U2 - 10.1021/acs.joc.8b01552
DO - 10.1021/acs.joc.8b01552
M3 - Article
C2 - 30021436
AN - SCOPUS:85050361079
SN - 0022-3263
VL - 83
SP - 10855
EP - 10863
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 18
ER -