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Regio‐ and Stereoselective Synthesis of Enynyl Boronates via Ruthenium‐Catalyzed Hydroboration of 1,4‐Diaryl‐Substituted 1,3‐Diynes
Author(s) -
Sokolnicki Tomasz,
Szyling Jakub,
Franczyk Adrian,
Walkowiak Jędrzej
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201900939
Subject(s) - chemistry , hydroboration , synthon , ruthenium , moiety , stereoselectivity , catalysis , iodobenzene , double bond , medicinal chemistry , combinatorial chemistry , stereochemistry , organic chemistry
A facile ruthenium‐catalyzed regio‐ and stereoselective hydroboration of symmetrical, aromatic 1,3‐diynes with pinacolborane towards 2‐boryl‐1,4‐diaryl‐buta‐1‐en‐3‐ynes and their further transformation into potassium trifluoroborate salts is presented. The reaction proceeded efficiently for 1,4‐diphenylbutadiynes with various substituents on the phenyl rings and heterocyclic 1,4‐di(thiophen‐3‐yl)buta‐1,3‐diyne. The resulting products were isolated and fully characterized ( 1 H, 13 C, 11 B and 1D NOESY NMR, IR, GC‐MS, HRMS or elemental analysis). Moreover, the crystal structure of an enynyl boronate was determined, proving the addition of boryl moiety at the internal carbon in the diyne, according to the anti‐Markovnikov rule. The results presented here are the first examples of selective catalytic monohydroboration of conjugated diynes. The products obtained due to the presence of the boryl group and the unsaturated bonds are potential synthons in the synthesis of natural compounds or active pharmaceutical ingredients (API). The model Suzuki coupling of 2‐boryl‐1,4‐diphenyl‐buta‐1‐en‐3‐ynes with iodobenzene was carried out to illustrate the utility of the resulting compounds.