2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO), N-Bromosuccinimide (NBS) and Bromine as Efficient Catalysts for Dithioacetalization and Oxathioacetalization of Carbonyl Compounds and Transdithioacetalization Reactions
作者:Nasser Iranpoor、Habib Firouzabadi、Hamid Reza Shaterian、M. A. Zolfigol
DOI:10.1080/10426500211712
日期:2002.5.1
6-tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS), and bromine as efficient catalysts for conversion of carbonyl compounds to their cyclic and acyclic dithioacetals and 1,3-oxathiolanes under mild reaction conditions are described. These catalysts are also used for efficient transdithioacetalization of acetals, diacetals, ketals, acylals, enamines, hydrazones, and oximes with high
Cadmium Iodide Catalyzed and Efficient Synthesis of Acetals under Microwave Irradiations
作者:Dhrubojyoti Dey Laskar、Dipak Prajapati、Jagir S. Sandhu
DOI:10.1246/cl.1999.1283
日期:1999.12
A new selective method of acetalization of aldehydes and ketones with 1,2-diols, 1,3-diols or alcohols mediated by cadmium iodide undermicrowaveirradiation is achieved in excellent yields.
2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a Versatile, Efficient, and Chemoselective Catalyst for the Acetalization and Transacetalization of Carbonyl Compounds, the Preparation of Acetonides from Epoxides and Acylals (1,1-Diacetates) from Aldehydes
The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
developed for the efficient synthesis of benzylidene acetal from aldehyde at room temperature. In this metal‐free method, Cl3CCN serves as a water scavenger as well as reaction medium and the acid catalyst is readily recovered and recycled. At room temperature, a wide variety of aryl and α,β‐unsaturated aldehydes react readily with functionalized diols and opticallyactive diols to furnish the corresponding
The Influence of Heteroatom-substituted Methyl Groups and of Vinyl Groups (CR<sub>2</sub>=CR—) Attached to C-2 of 1,3-Dioxolanes on the Ease and Direction of Hydrogenolysis of the 1,3-Dioxolanes by AlH<sub>2</sub>Cl, AlH<sub>3</sub>, or LiAlH<sub>4</sub>
作者:H. A. Davis、R. K. Brown
DOI:10.1139/v71-422
日期:1971.8.1
AlH2Cl or AlH3 in diethyl ether at room temperature reduces 2-vinyl- or 2-[alkyl (or aryl) substituted vinyl]-1,3-dioxolanes to only the β,γ-unsaturated alkyl β-hydroxyethyl ether, the product expected from hydride ion addition to C-2 of the 1,3-dioxolane. The ease of hydrogenolysis increases with increasing alkyl (or aryl) substitution on the 2-vinyl group.LiAlH4 in diethyl ether at room temperature, or
2-甲基-1,3-二氧戊环的甲基上的杂原子取代基阻碍了 2-取代的 1,3-二氧戊环的醚溶液的 AlH2Cl 的氢解速率。杂原子在降低氢解容易度方面的有效性是 H < S < O < Br < NR2。这种延迟被认为是由于杂原子的电负性和/或一些 AlH2Cl 与杂原子的配位引起的过渡态不稳定导致中间氧碳离子。AlH2Cl 或 AlH3 在室温下乙醚中将 2-乙烯基-或 2-[烷基(或芳基)取代的乙烯基]-1,3-二氧戊环还原为仅 β,γ-不饱和烷基 β-羟乙基醚,预期产物是氢阴离子加成到 C-2 1,3-二氧戊环。