[see reaction]. Mild and highly selective one-pot procedures for obtaining phosphoranes that exhibit reversed (O-cis) apicophilicity are described. On the basis of the procedures, O-cis phosphorane bearing an aryl group (R = 2,4,6-tri-i-propylphenyl) could be isolated for the first time; the procedure is also applicable for alkyl derivatives. Particularly effective was the use of I2 as an oxidizing reagent.

P–H spirophosphorane 4 bearing two Martin ligands was converted to dianions (5a–n), bearing R groups, with excess organolithium reagents (RLi). Subsequent oxidation with I2 at ambient temperature gave anti‐apicophilic (O‐cis) spirophosphoranes 2a–n. All anti‐apicophilic phosphoranes 2a–n isomerized irreversibly to the O‐trans spirophosphoranes 3a–n, respectively. For 2,6‐dialkylphenyl derivatives 2k–n, the barrier for pseudorotation between enantiomers 2‐RP and 2‐Sp was rather high, and thus the interconversion could not be observed on the NMR timescale. The activation parameters for the pseudorotation of the triisopropylphenyl (TIP) derivative 2n to 3n were almost identical with those of nBu derivative 2b to 3b, i.e., ΔH‡ = 21.3 kcal mol–1, ΔS‡ = –9.4 eu. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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