Naphtho[1,8-b,c]phosphete and 1,2-Diphosphaacenaphthene from the Reaction of 1,8-Dilithionaphthalene with RPCl2

Abstract

Strained rings and metal insertions: The product of the reaction between 1,8‐dilithionaphthalene and RPCl2 differs depending on the R group on the phosphorus atom. PhPCl2 gave (PhP)2‐peri‐bridged naphthalene, while iPr2NPCl2 gave the iPr2‐bridged compound (see scheme). The reactivity of the new compounds with transition‐metal complexes is also discussed.

Preparation and reaction of phosphorus peri-bridged naphthalenes and their adducts with Lewis acids

“…X-ray structures of 3a [7], 3b, and 4-6, and 7 were illustrated in Figs. 1 and 2, respectively, with numbering schemes adopted.…”

“…On the other hand, several research groups and we reported that a low valent transition metal such as a zerovalent platinum complex reacts with a strained phosphaheterocyle coordinating to a metal fragment to give a ring-expanded product with a platinum fragment inserted into a P-C bond [14,15]. Thus, 7 in which 3a is coordinating to a W(CO) 5 fragment was allowed to react with Pt(PPh 3 ) 4 [7]. 31 The two signals at 21 and 29 ppm could be assigned to PPh 3 ligands coordinating to the platinum and tungsten centers, respectively, whereas the signal at 88 ppm was assigned to the phosphorus moiety derived from 7.…”

“…at 75 and 22 ppm [7]. The former signal accompanied by the satellite signals due to 183 W and 195 Pt could be assigned to the phosphorus atom bridging tungsten and platinum centers.…”

“…On the other hand, the strained phosphorus heterocycles have attracted considerable interest owing not only to their peculiar structures and reactivities, but also to their utilities as a ligand toward a variety of transition metal fragments [6]. Recently, we have successfully prepared a phosphorus version of single-atom peri-bridged naphthalene (naphtho [1,8-bc]phosphete), as communicated briefly [7]. Here, details of the preparation, structural properties, and some reactivities are reported for R 2 NP peri-bridged naphthalenes and their adducts with some Lewis acids.…”

“…A similar reaction of 2 with Et 2 NPCl 2 also gave the corresponding peri-bridged product 3b in a much lower yield, the reason for which is not clear. On the other hand, the reaction with PhPCl 2 gave not a desired single-atom-bridged species, but (PhP) 2 -brigded naphthalene having a five-membered ring as reported previously [7,11].…”