91118-20-6Relevant academic research and scientific papers
Sulfoxide-directed metal-free ortho-propargylation of aromatics and heteroaromatics
Eberhart, Andrew J.,Shrives, Harry J.,álvarez, Estela,Carr?r, Amandine,Zhang, Yuntong,Procter, David J.
supporting information, p. 7428 - 7434 (2015/05/13)
Abstract A sulfoxide-directed, metal-free ortho-propargylation of aromatics and heteroaromatics exploits intermolecular delivery of a propargyl nucleophile to sulfur followed by an intramolecular relay to carbon. The operationally simple cross-coupling procedure is general, regiospecific with regard to the propargyl nucleophile, and shows complete selectivity for products of ortho-propargylation over allenylation. The use of secondary propargyl silanes allows metal-free ortho-coupling to form carbon-carbon bonds between aromatic and heteroaromatic rings and secondary propargylic centres. The 'safety-catch' nature of the sulfoxide directing group is illustrated in a selective, iterative double cross-coupling process. The products of propargylation are versatile intermediates and they have been readily converted into substituted benzothiophenes. A sulfoxide-directed, metal-free ortho-propargylation of aromatics and heteroaromatics exploits intermolecular delivery of a propargyl nucleophile to sulfur followed by an intramolecular relay to carbon (see scheme). The process allows metal-free ortho-coupling to form carbon-carbon bonds between aromatic and heteroaromatic rings and propargylic centres.
The stereochemistry of the vinylogous Peterson elimination
Fleming, Ian,Morgan, Ian T.,Sarkar, Achintya K.
, p. 2749 - 2763 (2007/10/03)
Base-induced eliminations of the vinylogous β-hydroxysilanes 7, 9, 11 and 12 are stereospecifically syn, giving largely the trans,trans-diene 8 from 7 and 11, the cis,trans-diene 10 from 9, and the trans,cis-diene 13 from 12. When a cis double bond is produced, it is selectively placed adjacent to the carbon atom that originally carried the hydroxy group. E2′ Reactions with silyl as the electrofugal group and acetate as the nucleofugal group, initiated by fluoride ion, are not stereospecific, but can be highly stereoselective in favour of the trans,trans-diene 8 when the carbon substituent at the silicon-bearing end is a cyclohexyl group and the double bond is cis, and in favour of the trans,cis-diene 13 when the carbon substituent at the silicon-bearing end is a methyl group and the double bond is trans. Attempts to use the Peterson reactions to make o-quinodimethanes stereospecifically failed, with no evidence of 1,4-elimination from the alcohols 40 and 41. The corresponding E2′ reaction from the esters using fluoride ion on the acetates or formates 46 and 47 gave stereoselectively the E,E-quinodimethane 48.
