Piperazine-and piperidine-functionalized polystyrenes have been examined as deblocking-scavenging agents for the 9-fluorenylmethyloxycarbonyl (Fmoc) amino-protecting group. Both commercial and synthesized polystyrenes have been used as supports. In order to introduce the active functional groups, (chloromethyl)polystyrene 2 was treated with ferf-butyl piperazine-l-carboxylate followed by acidic deblocking (HCl/dioxane) or, alternatively, was directly animated by means of a 10 molar excess of piperazine or l,3-bis(4-piperidino)propane. Compounds 7-9 were examined as cross-linking agents in the preparation of appropriate reagents. Most suitable were reagents prepared from commercial macroreticular resins or those cross-linked via DVT (8). Proof that the DBF liberated in the deblocking process was scavenged (partially) by the active secondary amine reagents 4 came from (a) a study of the successful regeneration of an active agent from 5 by treatment with alkali (H20-dioxane) and (b) liberation of 9-methylfluorene from 5 by hydrogenation (NH4OCHO/Pd-C).

An efficient procedure is described that leads to pure (SP)‐O‐l‐menthylphenylthiophosphinate. The absolute configuration of this diastereomer was assigned by chemical correlation and confirmed by X‐ray crystallography. The reaction of the isomer with phenyl azide, leading to amidate, is a new variant of the stereoselective Staudinger reaction. Addition of elemental selenium to the (SP)‐thiophosphinate led to diastereomeric O‐l‐menthylphenylselenophosphonothioic acid, which was finally oxidized to the diastereomeric (RP1,RP2)‐bis‐[O‐l‐menthylphenylphosphonothionyl] diselenide. The diselenide structure was unambiguously confirmed by 31P NMR spectroscopy.

No abstract

No abstract

No abstract

Reactions of CF3SSCF3(X = S, Se) with the Esters of Phosphoric Acid Reactions of CF3XXCF3(X = S, Se) with (CH3O)2PR give CF3SP(O)(OCH3)R [1a: R = CH3O, 1C: R = CH3)2N]. Similarly CF3SeSeCF3 reacts with (CH3O)3P to form the corresponding CF3SeP(O)‐(OCH3)2(2a). If CF3SSCF3 is combined with (C2H5O)2P(O)H good yields of CF3SP(O)(OC2H5)2 (1b) are obtained. On heating 1b decomposes to FP(O)(OC2H5)2. IR and 19F NMR data of the newly prepared substances are presented.

No abstract

No abstract