Intramolecular hetero Diels–Alder reaction of 1-thiabutadienes, 1-aryl-3-[2-(alkenyloxy)phenyl]propene-1-thiones and 2-[2-(alkenyloxy)benzylidene]-3,4-dihydronaphthalene-1(2H)-thiones

Abstract

a,P-Unsaturated thioketones 4 , 5 and 9, which are formed in situ by thionation of the corresonding ketones, undergo intramolecular hetero Diels-Alder reactions with high regio-and diastereo-selectivities (transkis) to give dihydrothiopyran-fused cycloadducts 6, 7 and 10.Intramolecular Diels-Alder reactions provide useful methods cedures However, IHDA reactions involving a thiofor construction of polycyclic systems, and have been widely carbonyl function have received little attention so far, applied in organic synthesis.1 Intramolecular hetero Diels-examples being restricted to the internal trapping thio-Alder (IHDA) reactions are also powerful synthetic pro-aldehyde intermediates by dienes.3 We now report the first

A Berzelius Reagent, Phosphorus Decasulfide (P4S10), in Organic Syntheses

“…Reaction of α,β-unsaturated ketone 14 with P 4 S 10 in CS 2 gave an intramolecular Diels−Alder reaction to yield the cyclo adduct 16 , possibly through the thione intermediate 15 (Scheme ) …”

“…Reaction of R,β-unsaturated ketone 14 with P 4 S 10 in CS 2 gave an intramolecular Diels-Alder reaction to yield the cyclo adduct 16, possibly through the thione intermediate 15 (Scheme 6). 74 Treatment of the diketone 17, having an R,β-unsaturated unit with P 4 S 10 in pyridine (dry), for 3-5 h at room temperature resulted in the formation of thiopyran ring 18 (Scheme 7). 75 On the other hand, it was reported that the treatment of the same ketone with P 4 S 10 in refluxing xylene yielded trithiapentalene 19.…”