First Asymmetric Hetero Diels−Alder Reaction of 1-Sulfinyl Dienes with Nitroso Derivatives. A New Entry to the Synthesis of Optically Pure 1,4-Imino-l-ribitol Derivatives

Abstract

Hetero Diels-Alder (HDA) cycloaddition of chiral 1-p-tolylsulfinyl-1,3-pentadiene with benzyl nitrosoformate, under mild conditions, yields 2H-1,2-oxazine 3 with complete regioselectivity and pi-facial diastereoselectivity. Sequential osmylation and protection of the resulting glycol gives the oxazine 5 which is directly transformed into enantiomerically pure 1,4,5-trideoxy-1,4-imino-L-ribitol 8 by reduction under Pd/C.

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

“…For example, the diene substituted with a pseudoephedrine-derived oxazolidine 170 gave the product in only modest stereoselectivity when reacted with benzyl nitrosoformate ( 171 ) [130]. On the other hand, the reaction of the chiral 1-sulfinyl diene 174 was found to be completely regio- and stereoselective when reacted with the same dienophile (Scheme 34) [131–132]. …”

Recent developments in chiral non-racemic sulfinyl group chemistry in asymmetric synthesis

“…115 This adduct was transformed into enantiomerically pure 1,4,5-trideoxy-1,4-imino-L-ribitol 145. Finally, the intramolecular hetero-Diels-Alder cycloaddition of an unsaturated ketone 146 derived from 3-methylcitronellal proceeds under Lewis acid catalysis to afford a mixture of the two diastereomeric adducts 147a and 147b (Scheme 59) in good to excellent yields (42 -100%) but with low to moderate diastereoselectivities (3 -60.6 % de).…”

Hetero‐Diels‐Alder‐Reaktionen von Nitrosocarbonylverbindungen als nützliches Verfahren in der organischen Synthese

“…Die acyclischen Diene 136 a [72,[146][147][148] und 136 b [75] wurden zur Synthese pyrrolidinbasierter Zuckerderivate eingesetzt (Schema 26). Die Cycloaddukte 137 wurden mit hohen Ausbeuten und Diastereoselektivitäten erhalten.…”

“…Hierdurch wiederum wird der chirale Rest 1-substituierter Diene räumlich weiter von dem eintretenden sperrigen Nitroso-Dienophil entfernt platziert. Nichtsdestotrotz wurden chirale acyclische Diene einschließlich des chiralen N-Dienyllactams 49, [72,73] des von Pseudoephedrin abgeleiteten Oxazolidins 50 [74] und des chiralen 1-Sulfinyldiens 51 [75,76] erfolgreich in asymmetrischen Nitroso-HDA-Reaktionen eingesetzt (Abbildung 8).…”