A metal-free and two-phase protocol for the Meyer-Schuster isomerization of propargyl alcohols to the corresponding α,β-unsaturatedcarbonylcompounds has been achieved in the presence of stoichiometric phosphorous acid aqueous solution, which produces the desired products in high yields with excellent stereoselectivity. Compared with the traditional methods, the procedure features broad scope of the
Expedient Synthesis of 4-Dialkylamino-5H-furan-2-ones by One-Pot Sequential Pd-Catalyzed Oxidative Carbonylation of 2-Yn-1-ols–Conjugate Addition-Lactonization
A novel synthesis of 4-dialkylamino-5H-furan-2-ones 3 starting from very simple building blocks, i.e., α-substituted 2-yn-1-ols 1, carbon monoxide, dialkylamines 2 and oxygen is reported. Reactions are carried out in 1,2-dimethoxyethane at 100 °C and under 20 atm (at 25 °C) of a 4/1 mixture of CO/air in the presence of catalytic amounts of PdI2 in conjunction with 10 equiv. of KI. Formation of 3 occurs
Alkynols undergo palladium-catalyzed aminocarbonylation leading to the direct formation of different heterocyclic derivatives, depending on the position of the OH group with respect to the triple bond. In the cases of 4-yn-1-ols and (Z)-2-en-4-yn-1-ols, the initially formed 2-ynamide intermediates, respectively, undergo cyclization leading to tetrahydrofuran derivatives or 2-furan-2-ylacetamides, respectively. In the case of 2-yn-1-ols, the aminocarbonylation products undergo intermolecular conjugate addition, followed by lactonization, leading to aminofuranones.
Reactions of propargylicalcohols bearing a terminalalkyne moiety with aromatic compounds in the presence of a catalytic amount of thiolate-bridged diruthenium complexes give the corresponding propargylated aromatic compounds in high yields with complete selectivity. Intramolecular reactions of propargylicalcohols bearing an aromatic moiety proceed smoothly to afford the cyclized products in high
Stereoselective Synthesis of Amphoteric <i>α</i>‐Haloalkenyl Boronates by Halogenative Semipinacol Rearrangement of B(MIDA)‐Propargylic Alcohols
作者:Li‐Cai Liu、Jiasheng Qian、Liyan Duan、Bin Wang、Fang‐Hai Tu、Qingjiang Li、Honggen Wang
DOI:10.1002/chem.202301011
日期:2023.7.11
Abstract
The facile synthesis of stereo‐defined and transformable functionality‐enriched building blocks is of great importance in modern organic chemistry, as it allows the rapid and divergent assembly of complex molecules. Herein a halogen electrophile (N‐bromosuccinimide and N‐iodosuccinimide) initiated semipinacol rearrangement reaction of B(MIDA)‐propargylic alcohols (MIDA=N‐methyliminodiacetyl) by aryl migration towards the synthesis of amphoteric α‐haloalkenyl boronates in moderate to good yields with excellent stereoselectivities is reported. The value of the products is evidenced by their ability to undergo divergent conversions to polysubstituted alkenes through manipulation of the C−B and C−X (X=Br, I) bonds and the carbonyl group.