Tetraalkoxy(hydroxy)phosphoranes were postulated as intermediates in the hydrolysis of alkyl(ary1)phosphates some time ago ['], but until now could only be synthesized in a few cases by oxidation of the corresponding hydrogen phosphoraned*]. Hydrolysis of the halospirophosphoranes 2a and 2b, obtainable by treating the trihalophosphor a n e~[~" ' l a and l b with dilithium perfluoropinacolate in neutral or alkaline aqueous ether solution, led to the hydroxyphosphorane 3 (m. p. = 72 "C, 78% yield) and potassium phosphorane oxide 5 (m. p. = 118 "C, 100% yield), respectively, without cleavage of the P-0 ring bonds to form a P=O bond. A tautomeric monocyclic form[21 of 3 is not observed. The methoxy derivative 4 (m. p. = 68 "C, 92% yield) is obtained in the same way using methanol. X 3 R = H 1, R = M e 2 5 Scheme I. @ I : I ; -196 to + 160°C (10 h) and + 2 0 " C (24 h), respectively, petroleum ether extraction, Et:O, sublimation: 2a (62%, m. p.=62"C) and 2b(43%, m.p.= 82"C), respectively. @ I mL of water or methanol is added to a stirred solution of 0.003 mol 2a or 2b in 20 mL of EbO; after 30 min the organic phase is separated off and the aqueous phase extracted three times with ether. The mixture was then dried over Na2S04, concentrated and the product recrystallized from Et,O. 0 1.0 g of KOH in 5 mL of water is added to a stirred solution of 0.01 mol 2a or 2b in 30 mL of EtrO; after 1 h the mixture is extracted three times with 20 mL of ether, dried over NarS04 and the solvent removed; yield 7.5 g 5.