The Diels-Alder cycloadditions of the alpha-acetoxynitroso dienophile in water are reported. The rapid and high yielding synthesis of structurally diverse 3,6-dihydro-1,2-oxazines complements the straightforward elaboration of aminoalcohols obtained from the alpha-acetoxynitroso derivative in anhydrous medium. A rationale for this solvent-dependent product distribution is proposed.
Cyclopentadiene nitroso adducts 1a and ent-1a were synthesised in good yields and good enantiomeric excess from chiral chloro-nitroso derivatives 4 and 5 in the d-mannose and d-ribose series, respectively. The thermal racemisation of these adducts occurred below room temperature. Some other chiral Diels–Alder nitroso adducts were prepared in the d-mandelic, l-prolinol and d-O-methylprolinol series
Crystalline 5-O-acetyl-2,3-isopropylidenedioxy-d-ribonolactone oxime (8) was synthesised from d-ribose in 40% overall yield. The chloronitroso dienophile 3b was obtained from 8 by oxidation with t-BuOCl and underwent asymmetric Diels-Alder reaction with cyclic and acyclic dienes 10-13 to give crystalline adducts 14a-17a in good yield and excellent enantiomeric excess (93-99%).
<i>P</i>-Nitrosophosphate Compounds: New N−O Heterodienophiles and Nitroxyl Delivery Agents
作者:Roy W. Ware、S. Bruce King
DOI:10.1021/jo001230z
日期:2000.12.1
evidence for nitroxyl, the one-electron-reduced form of nitric oxide. An asymmetric P-nitrosophosphate reacted with 1,3-cyclohexadiene to form a mixture of diastereomeric cycloadducts (19 and 20) in a 1.6:1 ratio. These results identify P-nitrosophosphates as new species that react similarly to acyl nitroso compounds, making them useful synthetic intermediates and potential nitroxyldeliveryagents.