The First Enantioselective Hetero Diels–Alder Reaction of Nitroso Compound Utilizing Tartaric Acid Ester as a Chiral Auxiliary

Abstract

The first regio- and enantioselective hetero Diels–Alder reaction of nitroso compound with dienol has been realized utilizing tartaric acid ester as a chiral auxiliary and the corresponding cycloadduct was obtained in complete regioselectivity with excellent enantioselectivity up to 92% ee.

N,N′-{[Ethane-1,2-diylbis(oxy)]bis(ethane-2,1-diyl)}bis(4-methylbenzenesulfonamide)

“…Similar to what was observed in a related structure (Polyakova et al, 1990), the O-CH 2 -CH 2 -O and N-CH 2 -CH 2 -O fragments adopt the gauche conformations with torsion angles of 76.0 (4) and 70.4 (3)° respectively. The S-O bond distances [1.423 (2) and 1.433 (2) Å] and S-N bond distance [1.608 (2) Å] are comparable to the values found in the literature (Ding et al, 2003;Polyakova et al, 1990)…”

“…For similar structures, see: Polyakova et al (1990); Ding et al (2003). Table 1 Hydrogen-bond geometry (Å , ).…”

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

“…Moreover, the reaction was completely regioselective [151]. In further experiments, one equivalent of n -propylzinc bromide, diisopropylzinc, ( R , R )-diisopropyl tartrate and the diene were mixed to form a complex before the nitroso dienophile was added.…”

5.10 Hetero-Diels–Alder Reactions

“…101 The dinuclear zinc complex and (cyclohex-1,3-dienyl)methanol forms zinc alkoxide 195, which reacts with nitrosobenzene to give the corresponding adduct 196 with complete diastereoselectivity in 94% yield with 92% ee. Since nitroso compounds exist in organic solvents as a monomer-azetoxy dimer equilibrium, the generation of chelated monomeric nitroso derivatives with a suitable LA is important for catalytic promotion of the enantioselective nitroso-Diels-Alder reaction.…”