Ethyl l,3-dithiolane-2-carboxylate

The Michael addition of ethyl l,3-dithiolane-2-carboxylate 330 to methyl vinyl ketone (MVK) followed by in situ aldol condensation afforded the spiro 1,3-dithiolane 337 (Equation 37) <1995H(41)507>. 

Ethyl l,3-dithiolane-2-carboxylate [20461-99-8] M 178.3, b 85 /0.1mm, d 1.250, n 1.538. Dissolve in CHCI3, wash with aqueous K2CO3, 2 x with H2O, dry over MgS04, filter, evaporate and distil [Hermann et al Tetrahedron Lett 2599 1973 Corey and Erickson J Org Chem 36 3553 1971]. 

A new route to pyridazine analogues of dihydropyridine calcium antagonists has been devised. Ethyl l,3-dithiolane-2-carboxylate was found to add efficiently, as its lithium salt, to benzylidene derivatives prepared from aryl aldehydes and diethylmalonate or ethyl acetoacetate the dithiolane adducts were readily deprotected using NBS (Scheme 98). The resultant diketo derivatives (121) were cyclized with hydrazine to give either 1,4-dihydropyridazines (122) or l,4,5,6-tetrahydro-6-... 

A high enantioselectivity is found in the aldol reaction of silylketene acetal derived from ethyl l,3-dithiolane-2-carboxylate with aldehydes, which is promoted by the oxaza-borolidinone 16. The products are readily desulfurized with the stereogenic center intact. With trichlorosilyl enolates as donors and a chiral phosphoric triamide 17 as catalyst, asymmetric aldol reactions with aldehydes are realized at low temperatures. ... 

Ethano-bridged phthalate ester 56 was obtained by the DA reaction in good yield and was converted to the BCOD-fiised triester 57a, the t-butyl ester group of which was removed by treatment with TFA (Scheme 15.10) [63]. The DA reaction of tosylacetylene (5a) and 2-methoxy-l,3-cyclohexadiene proceeded smoothly to afford a diastereomeric mixture (5 1) of bicyclo[2.2.2]octenone 58 in 73% yield after hydrolysis by silica gel [64]. Diastereomeric 58 was quantitatively converted to dithiolane, which was subject to the ring expansion reaction with tellurium tetrachloride [65]. Dihydro-1,4-dithiin 59 was obtained in 74% yield. The Barton-Zard reaction of 59 with ethyl isocyanoacetate afforded pyrrole-carboxylate 60a (77% yield), which was transformed to both a-hydroxymethylpyrrole 60b and a-firee pyrrole 60c in good yields. 

---