Palladium-catalyzed highly regioselective 6-exo-dig cyclization and alkenylation of ortho-ethynylanilides: the synthesis of polyene-substituted benzo[d][1,3]oxazines
作者:Zhong-Jian Cai、Chao Yang、Shun-Yi Wang、Shun-Jun Ji
DOI:10.1039/c5cc06510k
日期:——
A Pd-catalyzed highly regioselective 6-exo-dig cyclization/alkenylation reaction of ortho-ethynylanilides has been developed.
A new copper-catalyzed oxidativeringclosure of ethynyl anilides with diaryliodonium salts was developed for the highly modular construction of benzoxazines bearing a fully substituted exo double bond. The oxidative transformation includes an unusual 6-exo-dig cyclization step with the formation of C–O and C–C bonds.
A convenient method to construct (Z)-oxazines via 6-exo-dig iodocyclization and synthesis of indolin-3-one
作者:Jaya Kishore Vandavasi、Kung-Kai Kuo、Wan-Ping Hu、Ho-Chanu Shen、Wei-Sheng Lo、Jeh-Jeng Wang
DOI:10.1039/c3ob41272e
日期:——
An efficient regio-, stereo- and chemo-specific synthesis of 1,3-benzoxazines via 6-exo-dig cyclization to afford the Z-isomer is reported. The structure and connectivity were confirmed unambiguously on the basis of 1H NMR, NOESY, and ORTEP. Furthermore, DFT studies revealed that the Z-isomer was more stable than the E-isomer. Iodine substituted 1,3-benzoxazines were very useful precursors for cross coupling reactions. Suzuki reaction was carried out successfully and the resulting product was transformed to 1-(4-nitrobenzoyl)-2,2-diphenylindolin-3-one in the presence of a Lewis acid.
据报道,通过 6-exo-dig 环化可有效合成 1,3-苯并恶嗪,得到 Z-异构体。结构和连接性在 1H NMR、NOESY 和 ORTEP 的基础上得到明确证实。此外,DFT 研究表明 Z 异构体比 E 异构体更稳定。碘取代的1,3-苯并恶嗪是用于交叉偶联反应的非常有用的前体。 Suzuki反应成功进行,所得产物在路易斯酸存在下转化为1-(4-硝基苯甲酰基)-2,2-二苯基二氢吲哚-3-酮。
F‐Tag Induced Acyl Shift in the Photochemical Cyclization of
<i>o</i>
‐Alkynylated
<i>N</i>
‐Alkyl‐
<i>N</i>
‐acylamides to Indoles**
3-Acylindoles with different substituents in positions N-1 and C-2 were successfully synthesized by cyclization of o-substituted N-alkyl-N-acylamides by photochemically induced 1,3-acyl shift.
The highly regio- and stereoselective 6-exo-dig mode cyclization of N-acyl-o-alkynylanilines producing 4-alkylidene-3,1-benzoxazines occurred unpredictably by use of a proper catalyst [Pd(OAc)(2)] and an effective additive (acetic acid) under suitable reaction conditions.