Synthesis of trisubstituted furans from 2-bromo-5-methylfuranvia halogen migrations and their selective preventions
摘要:
New trisubstituted furans exhibiting two different substitution patterns were synthesized via lithiation of 2-bromo-5-methylfuran. Choice of appropriate reaction parameters enabled selective halogen dance reactions, affording 2-substituted 3-bromo-5-methylfurans upon quenching with various electrophiles. Moreover, from the same starting material also complete prevention of halogen migration could be achieved, thus providing selective access to 3-substituted 2-bromo-5-methylfurans.
Vilsmeier–Haack-Initiated Formylative Rearrangement of Spirodioxo-lan-5-ones into Functionalized 4,5,6,7-Tetrahydrobenzofurans
作者:Svetlana A. Varenichenko、Victor Markov、Jonas F. Goebel、Lukas J. Gooßen、Oleg K. Farat
DOI:10.1021/acs.joc.3c02042
日期:2024.3.1
furans can be synthesized in a single step from substituted dioxolan-5-ones by reacting with Vilsmeier–Haack reagents. These reagents are generated from POCl3 or PBr3 and DMF. The reaction cascade is mechanistically complex and involves deoxyhalogenation, iminomethylation, and electrophilic rearrangement steps, which are facilitated by the DMF solvent. The synthesis of hard-to-access 4,5,6,7-tetrahydrobenzofurans