Three-Component Coupling Reactions of Aryne, DMSO, and Activated Alkyne: Stereoselective Synthesis of 2-[(o-Methylthio)aryloxy]-Substituted Dialkyl Maleates

Abstract

A transition-metal-free coupling reaction of aryne, DMSO, and activated alkyne for the synthesis of 2-[(o-methylthio)­aryloxy]-substituted dialkyl maleates is reported. This cascade process is associated with several bond cleavage as well as bond formation reactions in one pot. One of our synthesized maleates has been unambiguously established by single-crystal XRD studies. This methodology allows preparation of trisubstituted vinyl ethers with excellent stereospecificity.

Recent Advances in Construction of C(sp2)–O Bonds via Aryne Participated Multicomponent Coupling Reactions

“…Following the same design principle, the Gogoi group developed a three-component protocol for the synthesis of dialkyl 2-[ o -(methylthio)aryloxy]maleates (Scheme 17 ). 34 In this case, the key 1,4-zwitterionic sulfonium intermediates were trapped by activated acetylenedicarboxylates to provide maleate derivatives in good yields along with high stereoselectivity. Moreover, DMSO-derived o -quinoid species could be captured with allyl bromides or vinyl bromides as 3rd components.…”

Aryne-Based Multicomponent Coupling Reactions

“…In 2014, Xiao developed MCR of arynes with dimethyl sulfoxide and -bromo carbonyl compounds to generate methyl thioethers 55. 68 Wang 69 and Gogoi 70 further expanded the transformation by employing arynes or activated alkynes as the third component to generate thioether derivatives 56. Using aryl allyl sulfoxide, Li accomplished the 1,2,3-trifunctionalization of arynes through a Claisen rearrangement to generate 57.…”

C–O/C–S difunctionalized benzene derivatives via multicomponent coupling of tetraynes

“…A possible mechanism underlying the formation of C-O/C-S difunctionalized benzene derivatives was proposed on the basis of the above results and previous literature 2,7,16 (Scheme 3). First, the HDDA-derived benzyne intermediate A underwent [2 + 2]…”

“…6 Gogoi's group designed an interesting three component reaction for 2-[(o-methylthio)aryloxy] substituted dialkyl maleate derivatives by using aryne, dimethyl sulfoxide and activated alkynes. 7 Many o-oxygen substituted aryl sulfides have been synthesized via aryne insertion into the SvO bond of sulfoxides. Two or more substituted o-alkylthio aryl esters are the important structural units in biologically active molecules and medicines, such as cox-2 inhibitors, 8 boldine, 9 and antimetabolites 10 (Scheme 1a).…”