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1,3‐Dipolar Cycloadditions of α ‐Diazo Ketones Derived from N ‐Protected ( S )‐Proline with Aromatic and Cycloaliphatic Thioketones
Author(s) -
Mlostoń Grzegorz,
Pipiak Paulina,
Linden Anthony,
Heimgartner Heinz
Publication year - 2015
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201400334
Subject(s) - chemistry , diazo , ylide , cycloaddition , stereocenter , proline , 1,3 dipolar cycloaddition , yield (engineering) , medicinal chemistry , stereochemistry , organic chemistry , amino acid , enantioselective synthesis , catalysis , biochemistry , materials science , metallurgy
Enantiomerically pure α ‐oxo diazo compounds derived from ( S )‐proline were used for 1,3‐dipolar cycloaddition with aryl and hetaryl thioketones, as well as with cycloalkanethiones. Whereas the reactions with hetaryl thioketones in boiling THF yield α , β ‐unsaturated ketones via a cascade of cycloaddition, 1,3‐dipolar electrocyclization, and desulfurization, the analogous reactions with thiobenzophenone and cycloalkanethiones result in the formation of 1,3‐oxathiole derivatives. In the latter case, the 1,5‐dipolar electrocyclization of the intermediate thiocarbonyl ylide is the key step of the reaction sequence. In all cases, the isolated products are optically active, i.e. , the multistep processes occur with retention of the stereogenic center incorporated via the use of ( S )‐proline as the precursor of the diazo compounds.