Formal [4+2] cycloaddition of di-tert-butyl 2-ethoxycyclobutane-1,1-dicarboxylate with ketones or aldehydes and tandem lactonization.
A catalytic amount of tin(IV) chloride catalyzed formal [4+2] cycloaddition reaction of di-tert-butyl 2-ethoxycyclobutane-1,1-carboxylate with ketones or aldehydes to give diethyl 6-ethoxydihydro-2H-pyran-3,3(4H)-dicarboxylates, whereas two equivalents of trimethylsilyl triflate promoted tandem [4+2] cycloaddition and lactonization to afford 3-oxo-2,6-dioxabicyclo[2.2.2]octane-4-carboxylate esters.
School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
Ryohei
R
Okado
Aya
A
Nowaki
Jun-Ichi
J
Matsuo
Hiroyuki
H
Ishibashi
D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003998:Dicarboxylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry; D017971:Tin Compounds / Q000737:chemistry
D000447:Aldehydes; D003998:Dicarboxylic Acids; D007659:Ketones; D007783:Lactones; D017971:Tin Compounds; C023599:stannous chloride