Synthesis of benzopyran prostaglandins, potent stable prostacyclin analogs, via an intramolecular mitsunobu reaction
作者:Paul A. Aristoff、Allen W. Harrison、Anne M. Huber
DOI:10.1016/0040-4039(84)80039-8
日期:——
Short syntheses of the extremely potent benzopyran prostacyclin mimics 26 and 27 are described using a novel intramolecular Mitsunobu reaction (e.g. 20 → 22) in the key step. This mild cyclization method was also applied to the synthesis of some simple chromans and benzofurans (34 – 38).
Twisted Amides as Selective Acylating Agents for Hydroxyl Groups under Neutral Conditions: Models for Activated Peptides during Enzymatic Acyl Transfer Reaction
The highly twisted amide 2 served as a selective acylating agent; for dials under neutral conditions. The reaction of primary-secondary dials with 2 led to the corresponding primary alkyl monopivalates. For dials containing alcoholic and phenolic hydroxyl groups, alcoholic hydroxyl groups were selectively acylated under neutral conditions, whereas, the opposite selectivity was observed under basic conditions, similar to the cases using acyl halides or acid anhydrides. Although 1 and 3 were unreactive to alcohols, 5-10 having substituent groups at C-4 were reactive to alcohols to give the corresponding acetates or benzoates.
REDUCTIONS WITH NICKEL-ALUMINUM ALLOY AND AQUEOUS ALKALI
作者:DOMENICK PAPA、ERWIN SCHWENK、BRADLEY WHITMAN
DOI:10.1021/jo01200a017
日期:1942.11
Selective hydrogenation of conjugated unsaturated ketones containing a hydroxyaryl substituent in the β-position
作者:V. N. Kovalenko、A. S. Pratsko
DOI:10.1134/s1070428017010055
日期:2017.1
A high selectivity was achieved in the Ni2B-catalyzed hydrogenation of alpha,beta-unsaturated ketones containing a hydroxyaryl (phenolic) substituent in the beta-position. The developed hydrogenation procedure was used to synthesize natural compounds of the phenylpropane series and their structural analogs.
Cyclopropenium-Activated Cyclodehydration of Diols
作者:Brendan D. Kelly、Tristan H. Lambert
DOI:10.1021/ol102980t
日期:2011.2.18
The dehydrative cyclization of diols to cyclic ethers via cyclopropenium activation is described. Using 2,3-diphenylcyclopropene and methanesulfonic anhydride, a series of 1,4- and 1,5-diols are rapidly cyclized to furnish tetrahydrofurans and tetrahydropyrans in high yield. Eleven total substrates are shown, including a gram scale cyclization of a diterpene derivative.