Thiophene endoperoxide 2, which was prepared by photooxygenation of thiophene 1, transfers a sulfur atom (up to 92%) to strained cycloalkenes to form thiiranes when thermolyzed in their presence. The diastereomeric pair cis/trans-cyclooctene (5b) reacted stereoselectively, which speaks for a concerted process rather than open dipolar and/or diradical intermediates. The set of chiral cyclooctenols 5c-e was also investigated, and the relative configurations of the respective thiiranes were assigned by chemical correlation and NMR spectral and X-ray analysis. The first-order kinetics of the process clearly shows that the endoperoxide 2 itself is not the sulfur-transferring species, but it is thermally transformed to the intermediates I and II. Whereas intermediate II is responsible for the competitive formation of elemental sulfur, intermediate I, presumably an oxathiirane, is the active sulfur-transferring species. The episulfidation was compared with the epoxidation by the related dimethyldioxirane, and both show the same qualitative trends in the diastereoselectivity and the reactivity toward the alkenes 5a-e.

Die bisher unbekannten Protonenlagen bei K2Zn(NH2)4 wurden röntgenographisch über Einkristalldaten bestimmt: P1, Z = 2, a = 6,730(1) Å, b = 7,438(1) Å, c = 8,019(2) Å, α = 72,03(2)°, β = 84,45(2)°, γ = 63,82(1)°, Z(F0) mit (F0)2 ≥ 3σ(F0)2 = 2166, Z(Parameter) = 96, R/RW = 0,032/0,039. Die Amidionen bilden das Motiv einer hexagonal dichtesten Kugelpackung. Darin sind in Ebenen parallel (010) abwechselnd alle Oktaederlücken durch Kalium oder geordnet 1/4 der Tetraederlücken durch Zink besetzt. Die Orientierung der Protonen an den Amidionen ist für diesen Strukturtyp (aufgefüllter CdI2‐Typ) charakteristisch.

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Die Struktur von Na2Mn(NH2)4 wurde röntgenograhisch über Einkristalldaten einschließlich der H‐Lagen bestimmt: P21/c, Z = 4, a = 6,331(1) Å, b = 14,542(3) Å, c = 7,212(1) Å, β = 116,29(1)°, Z(F0) mit (F0)2 ≥ 3σ(F0)2 = 1343, Z(Parameter) = 96, R/RW = 0,023/0,029. Die Verbindung kristallisiert in einem neuen Strukturtyp. Die Amidionen bilden innerhalb von Schichtenpaketen das Motiv einer hexagonal dichtesten Kugelpackung. In ihr sind in einzelnen Ebenen abwechselnd entweder alle Oktaederlücken durch Natrium oder geordnet 1/4 der Tetraederlücken durch Mangan besetzt.

[reaction: see text] Sultene 1 reacts with cyclic alkenes under mild Lewis acid catalysis to form thiiranes diastereoselectively. With 1-methoxycyclooctene as sulfur acceptor, an unexpected insertion product is formed, which provides valuable mechanistic insight into the sulfur-transfer process.