29539-19-3Relevant articles and documents
Regio- and stereoselective intramolecular hydroalkoxylation of aromatic alkynols: an access to dihydroisobenzofurans under transition-metal-free conditions
Yu, Shu-Yan,Gao, Li-Hong,Wu, Jing-Xin,Lan, Hong-Bing,Ma, Yi,Yin, Zhi-Gang
, p. 3303 - 3310 (2020/04/27)
An efficient, transition-metal-free method to synthesize dihydroisobenzofuran derivatives via intramolecular hydroalkoxylation of aromatic alkynols with the promotion of cesium carbonate has been developed. The reaction proceeds regioselectively with exclusive formation of 5-exo-dig product, and only Z-isomer of the new generated double bond is observed. This new protocol features with milder reaction conditions, more convenient operation and satisfactory selectivities.
Synthesis of dihydroisobenzofurans via palladium-catalyzed sequential alkynylation/annulation of 2-bromobenzyl and 2-chlorobenzyl alcohols under microwave irradiation
Buxaderas, Eduardo,Alonso, Diego A.,Njera, Carmen
supporting information, p. 3415 - 3421 (2015/01/09)
The palladium-catalyzed synthesis of dihydroisobenzofurans has been performed by sequential Sonogashira cross-coupling/cyclization reactions between terminal alkynes and 2-(hydroxymethyl)bromoand chlorobenzenes in methanol as solvent at 130 °C under microwave irradiation. A 4,4'-dichlorobenzophenone oxime-derived chloro-bridged palladacycle is an efficient pre-catalyst to perform this tandem process using 2-dicyclohexylphosphanyl-2',4',6'-triisopropylbiphenyl (Xphos) as ancillary ligand and potassium hydroxide as base in the absence of a copper cocatalyst. Under these conditions, functionalized 2-bromo- and 2-chlorobenzaldehydes are also suitable partners in the domino process affording phthalans in good yields. All the reactions can be performed under air and employing reagentgrade chemicals under low loading conditions (1 mol% Pd).
Alkaline earth catalysis of alkynyl alcohol hydroalkoxylation/cyclization
Brinkmann, Christine,Barrett, Anthony G. M.,Reid, Stephanie,Hill, Michael S.,Procopiou, Panayiotis A.
, p. 7287 - 7297,11 (2020/09/02)
Heavier alkaline earth bis(trimethylsilyl)amides [Ae{N(SiMe 3)2}2]2 (Ae = Ca, Sr, Ba) are shown to act as effective precatalysts for the regioselective intramolecular hydroalkoxylation/cyclization of a wide range of alkynyl and allenyl alcohols. In the majority of cases, cyclization of alkynyl alcohols produces mixtures of the possible endo- and exocyclic enol ether products, rationalized as a consequence of alkynylalkoxide isomerization to the corresponding allene derivatives. Cyclization rates for terminal alkynyl alcohols were found to be significantly higher than for substrates bearing internal alkynyl substituents, while the efficacy of cyclization was in general found to be determined by a combination of stereoelectronic influences and the thermochemical viability of the specific alkaline earth metal catalysis, which we suggest is determined by the individual M-O bond strengths. Kinetic studies have provided a rate law pertaining to a pronounced catalyst inhibition with increasing [substrate], indicating that turnover-limiting insertion of C-C unsaturation into the M-O bond requires the dissociation of substrate molecules away from the Lewis acidic alkaline earth center.
