TY - JOUR
T1 - (1R,3R)-2-methylene-1,3-dithiolane 1,3-dioxide: a highly reactive and highly selective chiral ketene equivalent in cycloaddition reactions with a broad range of dienes
AU - Aggarwal, V.K.
AU - Gültekin, Z.
AU - Grainger, R.S.
AU - Adams, H.
AU - Spargo, P.L.
PY - 1998
Y1 - 1998
N2 - The chiral ketene equivalent trans-2-methylene-1,3-dithiolane 1,3-dioxide has been prepared in racemic and enantiomerically pure form in four steps. The key step in the asymmetric synthesis utilised a Modena asymmetric oxidation of 2-benzyloxymethyl-1,3-dithiolane which gave the trans bis-sulfoxide with high diastereocontrol (91∶9 in favour of trans) and high enantiocontrol (>97% ee). The ketene equivalent shows high selectivity (>97∶3) in Diels–Alder reactions with a range of simple dienes (cyclopentadiene, furan, 1-methoxybutadiene, Danishefsky’s diene, 1-methoxycyclohexa-1,3-diene) and shows high reactivity as it is able to undergo cycloadditions with notoriously unreactive dienes (cyclohexa-1,3-diene, 90∶10 selectivity; 2H-pyran-2-one, 94∶6 selectivity). Dihydropyridines also participated in cycloaddition reaction but with only moderate selectivity (73∶27). The Diels–Alder adducts can be readily deprotected to return the carbonyl group using a two step sequence involving reduction followed by hydrolysis.
AB - The chiral ketene equivalent trans-2-methylene-1,3-dithiolane 1,3-dioxide has been prepared in racemic and enantiomerically pure form in four steps. The key step in the asymmetric synthesis utilised a Modena asymmetric oxidation of 2-benzyloxymethyl-1,3-dithiolane which gave the trans bis-sulfoxide with high diastereocontrol (91∶9 in favour of trans) and high enantiocontrol (>97% ee). The ketene equivalent shows high selectivity (>97∶3) in Diels–Alder reactions with a range of simple dienes (cyclopentadiene, furan, 1-methoxybutadiene, Danishefsky’s diene, 1-methoxycyclohexa-1,3-diene) and shows high reactivity as it is able to undergo cycloadditions with notoriously unreactive dienes (cyclohexa-1,3-diene, 90∶10 selectivity; 2H-pyran-2-one, 94∶6 selectivity). Dihydropyridines also participated in cycloaddition reaction but with only moderate selectivity (73∶27). The Diels–Alder adducts can be readily deprotected to return the carbonyl group using a two step sequence involving reduction followed by hydrolysis.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33748648417&partnerID=MN8TOARS
U2 - 10.1039/A804607G
DO - 10.1039/A804607G
M3 - Article
SP - 2771
EP - 2782
JO - Journal of the Chemical Society - Perkin Transactions 1
JF - Journal of the Chemical Society - Perkin Transactions 1
IS - 17
ER -