In dimethyl sulfoxide I ,2,3-trienyl ethers RRC=C=C=CHOCHs (with R and R = alkyl or RR'C = cyclohexyl) are isomerised by potassium rertbutoxide, first to 1,2,4-and then to 1,3,5-trienyl ethers. In the case of R R C = cyclohexyl, thus with / \=C=C=CHOCH3, elimination of methanol takes place and further isomerisation finally leads to aromatisation to 1-propenylbenzene. Acid hydrolysis of CHz=C(CHa)CH=C=CHOCHs in dimethyl sulfoxide affords the aldehyde CHz=C(W3)CH=CHCHO.The 1,2,3-and 1,2,4-trienyl ethers have been metallated in the 1-position by lithium amide and butyllithium, and subsequently alkylated or hydroxyalkylated.-

Treatment of the carbinols (CH3)2C=C=C=C(OCH3)CR1R2(OH) (I) with potassium tert-butoxide in dimethyl sulfoxide gives derivatives of furan (111)if R2 = H and derivatives of 2,Sdihydrofuran (11) if R1 and R2 are both alkyl or if R1R2C = cyclohexyl. Acid-catalysed hydrolysis of I1 and 111 affords derivatives of 3-0~0-2~3-dihydrofuran (IV).Potassium amide in liquid ammonia, when used in excess, causes isomerisation of I into CHz=C(CH3)CH=C=C(OCH3)CR1R2(0H) (Ia).In a previous publication 1 we described, inter alia, the preparation of 1 ,2,3-trienyl ethers and some base-catalysed conversions with these compounds. For example (CH3)zC=C=C=CHOCH3 was found to isomerise into CHz=C(CH3)CH= C=CHOCH3 and (CHz)sC= C=C=CHOCH3 into HzC=CH-C(CZH~)=CH-CH=CHOCH~. This paper deals with the behaviour of carbinols, derived from (CH~)ZC=C=C=CHOCH~ towards potassium tert-butoxide in dimethyl sulfoxide (DMSO) and towards potassium amide in liquid ammonia. Addition of the carbinols I to a solution of a catalytic (,-10 molar %) amount of K O Z -C~H~ in DMSO resulted in a considerable rise in temperature.Working up after about 15 minutes afforded the 2,5-dihydrofurans TI in the case where R1 and R2 were both alkyl or R l R T = cyclohexyl, and a mixture of comparable amounts of derivatives of 2,5-dihydrofuran I1 and furan I11 in the other cases.When heating was continued for two hours at 80°, only furans of type 111 could be isolated in the latter cases.

Bei der Reaktion der Carbinole (Ia) und (Ib) mit K‐tert‐butoxid in Dimethylsulfoxid werden die Furane (IIIa) (91%) und (IIIb) (84%) gebildet.