hexahydro-2'3a-dimethylspiro[1,3-dithiolo[4,5-b]furan-2,3'(2'H)-furan] Spiro[2,4-Dithia-1-methyl-8-oxabicyclo[3,3,0]octane-3,3'-(1'oxa-2'methyl)cyclopentane Spiro1,3-dithiolo4,5-bfuran-2,3(2H)-furan, hexahydro-2,3a-dimethyl- spiro{2,4-dithia-1-methy-8uxaBicyclo[3,3,0]ocatane-3,3-(1-oxa-2-methyl)cyclopantene} 3a,4',5,5',6,6a-Hexahydro-2',3a-dimethylspiro[1,3-dithiolo[4,5-b]furan-2,3'(2'H)-furan] 2',3-Dimethyl-3',4-dioxa-2,8-dithiabicyclo[3.3.0]octanespirocyclopentane spiro[2.4-dithia-1-methyl-8-oxabicyclo[3.3.0]octane-3-3'-(1'-oxa-2'-methyl)cyclopentane plus spiro[dithia-6-methyl-7-oxabicyclo[3.3.0]octane-3-3'-(1'-oxa-2-methyl)cyclopentane] 2',3a-dimethylspiro[6,6a-dihydro-5H-[1,3]dithiolo[4,5-b]furan-2,3'-tetrahydrofuran]