Niobium(V) Chloride-Zinc


[10026-12-7]  · Cl5Nb  · Niobium(V) Chloride-Zinc  · (MW 270.15) (Zn)

[7440-66-6]  · Zn  · Niobium(V) Chloride-Zinc  · (MW 65.37)

(synthesis of allylic alcohols, dienes, and naphthols; selective reduction of alkynes to (Z)-alkenes)

Solubility: sol THF-PhH, DME-PhH, HMPA.

Preparative Method: generated in situ from pentachloroniobium and Zinc.

Handling, Storage, and Precautions: should be prepared and used under an inert atmosphere of nitrogen or argon.

A combination of NbCl5 with Zn in either THF or DME presumably generates a NbCl3(L)2 species, which reacts with alkynes to give intermediate metallacyclopropenes.1 These metallacyclopropenes can then be quenched with NaOD/D2O to give cis-dideuterated alkenes (eq 1). In addition, reaction of the metallacyclopropenes with aldehydes or ketones gives either allylic alcohols or dienes, and reaction with phthalic dicarbaldehyde yields naphthols. The latter two transformations can be effected in higher yield using TaCl5-Zn and NbCl3(DME), respectively.

1. (a) Kataoka, Y.; Takai, K.; Oshima, K.; Utimoto, K. JOC 1992, 57, 1615. (b) Kataoka, Y.; Miyai, J.; Oshima, K.; Takai, K.; Utimoto, K. JOC 1992, 57, 1973. (c) Kataoka, Y.; Miyai, J.; Tezuka, M.; Takai, K.; Oshima, K.; Utimoto, K. TL 1990, 31, 369.

Carrie A. Roskamp & Eric J. Roskamp

Northwestern University, Evanston, IL, USA

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