A novel synthesis of 2,3-dihydro-1<i>H</i>-thieno[3,4-<i>b</i>]pyrroles<i>via</i>ring transformation of cyclic sulfonium ylides by titanium(IV) chloride-triethylamine system
A series of cyclic sulfonium ylides 4a-h reacted with titanium(IV) chloride in the presence of triethyl-amine to give the corresponding fused 2,3-dihydro-1H-thieno[3,4-b]pyrroles 5a-h, via a ring opening and recyclization. In contrast, treatment of compounds 4a, 4b, 4e and 4f with titanium(IV) chloride, triethy-lamine and dimethylamine hydrochloride gave the corresponding thiophenes 6a, 6b, 6e and
在三乙胺的存在下,一系列环状sulf基化物4a-h与氯化钛(IV)反应,得到相应的稠合的2,3-二氢-1 H-噻吩并[3,4- b ]吡咯5a-h,通过开环和回收利用。相反,用氯化钛(IV),三乙胺和盐酸二甲胺处理化合物4a,4b,4e和4f得到相应的噻吩6a,6b,6e和6f。此外,化合物6a和6b容易用氢化钠环化,得到相应的5a和5b。
Synthesis of 3,4-dihydro-2<i>h</i>-thiopyrans by the reaction of 4,5-dihydrothiophenium-1-bis[ethoxy(and methoxy)carbonyl]methylides with sodium iodide
Sulfoniumylides 1a-h reacted with sodium iodide to afford the corresponding thiopyrans 2a-h. On the other hand, compounds 1a-d were treated with thionyl chloride to give the ring opening products 3a-d. The reaction of compounds 3a-d with sodium iodide and triethylamine provided the corresponding thiopyrans 2a-d.