Twelve-membered B < inf > 2 < /inf > Si < inf > 4 < /inf > O < inf > 6 < /inf > borasiloxane macrocycles

Abstract

A one pot three component reaction of boric acid, diphenylsilanediol and functionalized alcoholic pyrazole in 1:1:1 stoichiometry using toluene as a solvent under reflux conditions afforded twelve-membered borasiloxane macrocycle [(Ph2Si)4(O)6(BR1PzR)2] {R1 = C6H4OH and R = H for 1, R1 = C6H4OH and R = CH3 for 2 R1 = C 10H6OH and R = H for 3} in moderate yields. Single crystal X-ray elucidation revealed the formation of a puckered twelve-membered ring system. ESI-MS studies indicate the stability of these macrocyclic systems in solution. © 2013 Elsevier B.V. All rights reserved.