Efficient and Complementary Methods Offering Access to Synthetically Valuable 1,2-Dibromobenzenes
作者:Vincent Diemer、Frédéric R. Leroux、Françoise Colobert
DOI:10.1002/ejoc.201001217
日期:2011.1
in particular, reactions based on the intermediate formation of benzynes. This report describes short sequences for the synthesis of various derivatives based on regioselective bromination, ortho-metalation, and halogen/metal permutations. 1,2-Dibromo-3-iodobenzene (2f), 1,2-dibromo-4-iodobenzene (4c), and 2,3-di-bromo-1,4-diiodobenzene (5e) act as intermediates in these syntheses.
Asymmetric ring-opening of oxabenzonorbornadiene with amines promoted by a chiral iridium-monophosphine catalyst
作者:Renshi Luo、Jianhua Liao、Ling Xie、Wenjun Tang、Albert S. C. Chan
DOI:10.1039/c3cc46009f
日期:——
A new iridium-monophosphine catalyst is found to be efficient for asymmetric ring-opening of benzonorbornadiene with amines, providing a series of chiral substituted dihydronaphthalenes in high yields (up to 98%) and excellent enantioselectivities (>99%).
Acid-Catalyzed Intramolecular Ring-Opening Reactions of Cyclopropanated Oxabenzonorbornadienes with Carboxylic Acid Nucleophiles
作者:William Tam、Angel Ho、Austin Pounder、Samuel Koh、Matthew P. Macleod、Emily Carlson
DOI:10.1055/a-1672-2260
日期:2022.3
(CPOBDs) to undergo ring-opening reactions in mild acidic conditions. The optimized reaction conditions involve the use of pTsOH in DCE at 90 °C. Two regioisomers are formed but the reactions are highly regioselective towards type 3 ring-opened products. It was observed that substitution at the C5 and aryl positions of CPOBD significantly hinders the ring-opening reactions leading to decreased yields of
An oxidative furan fragmentation reaction is described, which provides facile and modular access to butenolides bearing a wide variety of appended remote functional groups, including olefins, halides, azides and aldehydes. The practical utility of this transformation is demonstrated by its ability to simplify the syntheses of known building blocks of eight biologically active natural products.
have developed a one-pot synthesis of benzo[b]fluorenones via a cobalt-catalyzed [3+2] annulation of oxabicyclic alkenes followed by a ring-opening/dehydration sequence in good to excellent yields. With the use of 2-(1-methylhydrazinyl)pyridine (MHP), first explored by our group as the bidentate directing group in C–H functionalization of benzoic hydrazides, the new reaction sequence proceeded smoothly
我们已经开发了一种通过一锅合成的苯并[ b ]芴酮的方法,该方法是通过钴催化的氧杂双环烯烃的[3 + 2]环化反应,然后以开环/脱水顺序进行的,收率很好。我们小组首先探索使用2-(1-甲基肼基)吡啶(MHP)作为苯甲酰肼的CH官能化中的双齿导向基团,新的反应顺序进行得很顺利,并能耐受各种官能团,具有便利的可扩展性。值得注意的是,氧气在反应系统中充当绿色氧化剂。仔细调整反应参数可确保通过二氢环氧苯并芴酮中间体的芳构化直接合成苯并[ b ]芴酮。