As an extension of methodology previously developed for the synthesis of vicinal amino alcohols, stereocontrolled synthesis of unsaturated vicinal diamines from Diels-Alder adducts of sulfur dioxide bis(imides) (la, lb) and various 1,3-dienes was investigated. The 3,6-dihydrothiazin-l-imine Diels-Alder adducts having a trans relationship of the sulfur and C-6 substituents stereospecifically afforded unsaturated vicinal diamines in high yields via ring opening with phenylmagnesium bromide to allylic sulfilimines which underwent [2,3]-sigmatropic rearrangement to sulfenamides. Desulfurization of the sulfenamide with trimethyl phosphite afforded (E)-threo diamines 11 and 12 from the Diels-Alder adducts of (E,E)-hexadiene 4 and 6, respectively, and (E)-erythro diamines 18 and 19 from the adducts of (E,Z)-hexadiene 7 and 9, respectively. In contrast, the epimeric thiazinimines 3 and 10, having a cis relationship of the sulfur and C-6 substituents, were relatively unreactive toward carbon nucleophiles, affording the expected diamine derivatives in only fair to poor yields. However, the “unreactive” cis-thiazin-1-imines 3, 5, 8, and 10 were found to undergo a facile thermal [2,3]-sigmatropic rearrangement to give thiadiazolidines 21, 22, 23, and 24, respectively, which were converted to the desired unsaturated diamine derivatives 11, 12,18, and 19 by sodium borohydride reduction in excellent yields. The reactivities of the Diels-Alder adducts are explained on the basis of the stereostructures of the Diels-Alder adducts, which were unambiguously determined by single-crystal X-ray analyses and 1H NMR lanthanide induced shift studies. The Diels-Alder reaction of 1,3-cyclohexadiene and bis(imide) lb was investigated, leading to cis-vicinal carbamate 33 in a good yield along with the interesting amino diene derivative 32.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry