3.6- Dihydro-l,2-dithiin

Reactions of cyclopentadienyl- and (pentmethylcyclopentadienyl)iron dicarbonyl 2-alkynyl complexes as well as cyclopentadienylmolybdenum tricarbonyl 2-alkynyl complexes with 4,5-diphenyl-3,6-dihydro-l,2-dithiin 1-oxide 111 were shown to yield transition metal-substituted five-membered ring thiosulfinate esters 112 in moderate to excellent yields (Scheme 27) <19910M2936, 1989JA8268>. These reactions are formal [3-1-2] cycloadditions. When... 

W(CO)s(NCMe) transformed vinylthiirane and substituted vinylthiiranes 201 into 3,6-dihydro-l,2-dithiins 202 in excellent yields (Scheme 55) <2000POL521, 1999JA3984, 1998JA1922, 1997OM1430, 19%JA10674>. Two equivalents of the vinylthiirane are required and 1 mol of butadiene is produced by transferring its sulfur to the other vinylthiirane molecule. In the absence of the catalyst or in the presence of W(CO)6, only traces of the 3,6-dihydro-l,2-dithiins... 

Vinyl-3,6-dihydro-l,2-dithiin 2-oxide has been isolated as one of the main components from garlic Allium sativum) <2001MI867>. Its structure was elucidated by NMR and MS. 

Only a few examples of ring syntheses by transformation of another ring have been published, as exemplified by the preparation of the sultines 168 by ring enlargement of five-membeted thiolane 1-oxides 166 (cf Section 8.10.9.2.3) and the 3,6-dihydro-l,2-dithiins 202 by catalytic transformation of vinylthiiranes 201 (cf Section 8.10.9.4.2). Because possibilities to synthesize six-membered rings with oxygen and/or sulfur as heteroatoms in 1,2-positions are rather limited, these reactions have been covered already in Section 8.10.9 together with alternative syntheses from alicyclic compounds. 

Dihydro-l,2-dithiin, with trinuclear Os clusters, 6, 744 Dihydrogen... 

Oxathiin 2,2-dioxides (sultones) (e.g., 150) are obtained by the addition of sulfur trioxide to dienes or by ringclosing metathesis (RCM) of sulfonates using the second-generation Grubbs ruthenium catalyst (Scheme 75) . The same catalyst was also successfully employed in the RCM of diallyl disulfide 151 which led quantitatively to 3,6-dihydro-l,2-dithiin 152 (Scheme 76) <20020L1767>. 

Photochemically generated diatomic sulphur added to l,2-bis(methylene)-cyclohexane to afford a 3,6-dihydro-l,2-dithiin. The dihydrodithiin (20) was formed by thermal rearrangement of a 1,3-dithiin. Addition of disulphur monoxide to 2,3-disubstituted buta-1,3-dienes yielded the rather unstable dihydrodithiin 1-oxides (21). 

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