TY - JOUR
T1 - BF3-Promoted Reactions of Cyclic 1,2-Diketones and Paraformaldehyde - New Structural Motifs by Multiple Hydroxymethylation and Acetal Formation
AU - Löbel, Johannes
AU - Herdtweck, Eberhardt
AU - Bach, Thorsten
PY - 2003/10/31
Y1 - 2003/10/31
N2 - The BF3-promoted reaction of paraformaldehyde with the cyclic 1,2-diketones 1, 3, 8 and 10 was studied. Under identical reaction conditions, the substrates yielded structurally different products depending on their ring size. 1,2-Cyclopentanedione (3a) was converted into the spiro compound 4 (49%) whereas its 3-methyl analog 3b gave a butterfly-like compound 5b (56%). A structurally related compound 2 was obtained (84%) by the reaction of 1,2-cyclohexanedione (1) with paraformaldehyde. 1,2-Cycloheptanedione (8) yielded the simple tricyclic acetal 9 (72%) whereas 1,2-cyclooctanedione (10) underwent a twofold hydroxymethylation in the α- and α′ -positions yielding the acetal 11 (53%). The structures of all new compounds were proven by NMR experiments and X-ray crystallography. The mechanism of product formation is discussed based on steric and electronic arguments.
AB - The BF3-promoted reaction of paraformaldehyde with the cyclic 1,2-diketones 1, 3, 8 and 10 was studied. Under identical reaction conditions, the substrates yielded structurally different products depending on their ring size. 1,2-Cyclopentanedione (3a) was converted into the spiro compound 4 (49%) whereas its 3-methyl analog 3b gave a butterfly-like compound 5b (56%). A structurally related compound 2 was obtained (84%) by the reaction of 1,2-cyclohexanedione (1) with paraformaldehyde. 1,2-Cycloheptanedione (8) yielded the simple tricyclic acetal 9 (72%) whereas 1,2-cyclooctanedione (10) underwent a twofold hydroxymethylation in the α- and α′ -positions yielding the acetal 11 (53%). The structures of all new compounds were proven by NMR experiments and X-ray crystallography. The mechanism of product formation is discussed based on steric and electronic arguments.
KW - Cyclization
KW - Heterocycles
KW - Lewis acids
KW - Prins reaction
KW - Synthetic methods
UR - http://www.scopus.com/inward/record.url?scp=0242427568&partnerID=8YFLogxK
U2 - 10.1002/ejoc.200300351
DO - 10.1002/ejoc.200300351
M3 - Article
AN - SCOPUS:0242427568
SN - 1434-193X
SP - 4146
EP - 4151
JO - European Journal of Organic Chemistry
JF - European Journal of Organic Chemistry
IS - 21
ER -