TY - JOUR
T1 - Incorporation of three or two distal double bonds at the methylene bridges of the calix[4]arene scaffold
AU - Shalev, Ori
AU - Biali, Silvio E.
N1 - Publisher Copyright: © 2014 American Chemical Society.
PY - 2014/9/19
Y1 - 2014/9/19
N2 - Partial oxidation of the 1,3-alternate atropisomer of p-tert-butylcalix[4]arene tetraacetate with CrO3 afforded mainly a mixture of trioxo- and tetraoxo-calix[4]arene tetraacetate derivatives. The trioxotetrahydroxy derivative 6 was isolated from the mixture after hydrolysis of the crude product, followed by trituration with ethanol. Trioxocalix[4]- arene adopts in the crystal a 1,2-alternate conformation. Acetylation or alkylation of the tetrahydroxytrioxocalix[4]arene 6 with acetic anhydride and 1-bromobutane, respectively, afforded exclusively a single atropisomer of the product, which in both cases were characterized as the 1,3-alternate form. Addition of MeLi to the tetramethyl and tetrabutyl ether of the trioxocalix[4]arenes followed by 3-fold elimination of water yielded calixarene derivatives possessing three exocyclic double bonds at the bridges. Reaction of the dioxotetramethoxy calix[4]arene 9b with MeLi followed by 2-fold elimination of water afforded calixarene 11 with a pair of distal exocyclic double bonds at the bridges. Both the tetramethyl ether derivatives 9b and 11 exist in solution as a mixture of the 1,2-alternate and 1,3-alternate conformers, but in the crystal both adopt a 1,2-alternate conformation.
AB - Partial oxidation of the 1,3-alternate atropisomer of p-tert-butylcalix[4]arene tetraacetate with CrO3 afforded mainly a mixture of trioxo- and tetraoxo-calix[4]arene tetraacetate derivatives. The trioxotetrahydroxy derivative 6 was isolated from the mixture after hydrolysis of the crude product, followed by trituration with ethanol. Trioxocalix[4]- arene adopts in the crystal a 1,2-alternate conformation. Acetylation or alkylation of the tetrahydroxytrioxocalix[4]arene 6 with acetic anhydride and 1-bromobutane, respectively, afforded exclusively a single atropisomer of the product, which in both cases were characterized as the 1,3-alternate form. Addition of MeLi to the tetramethyl and tetrabutyl ether of the trioxocalix[4]arenes followed by 3-fold elimination of water yielded calixarene derivatives possessing three exocyclic double bonds at the bridges. Reaction of the dioxotetramethoxy calix[4]arene 9b with MeLi followed by 2-fold elimination of water afforded calixarene 11 with a pair of distal exocyclic double bonds at the bridges. Both the tetramethyl ether derivatives 9b and 11 exist in solution as a mixture of the 1,2-alternate and 1,3-alternate conformers, but in the crystal both adopt a 1,2-alternate conformation.
UR - http://www.scopus.com/inward/record.url?scp=84911446327&partnerID=8YFLogxK
U2 - https://doi.org/10.1021/jo501177g
DO - https://doi.org/10.1021/jo501177g
M3 - مقالة
SN - 0022-3263
VL - 79
SP - 8584
EP - 8591
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 18
ER -