1-Pentynylcopper(I)-Hexamethylphosphorous Triamide1

[67840-54-4]  · C17H43CuN6P2  · 1-Pentynylcopper(I)-Hexamethylphosphorous Triamide  · (MW 457.15)

(freely soluble, nontransferable dummy ligand employed in mixed lithioorganocuprates2)

Physical Data: clear solution in ether (also see entries for 1-Pentynylcopper(I) and Hexamethylphosphorous Triamide).

Solubility: sol ether, THF at -78 °C.

Preparative Methods: addition of P(NMe2)3 (HMPT) to pentynylcopper in ether or THF at 25 °C.2

Handling, Storage, and Precautions: all copper(I) acetylides are potentially explosive when dry. Use in a fume hood.

Mixed Organocuprates.

Since initial disclosures by Corey,2 copper(I) acetylides have found widespread use for the preparation of mixed lithiocuprates RrRtCuLi where Rt is a transferable group and Rr is a residual dummy group.2-13 Copper(I) acetylides can be prepared in pure form and, due to the stabilizing d-p backbonding that exists between copper and alkynes connected by a s-bond, alkynes represent ideal nontransferable ligands. For preparation of mixed cuprates (RrRtCuLi), alkynylcopper species (RrCu) are combined with appropriate alkyllithium reagents (RtLi). The relative insolubility of pentynylcopper in ether or THF at low temperature precluded its use for this purpose; however, the bis(HMPT) complex is soluble and reactive to alkyllithium reagents at -80 °C. The HMPT residues are water-soluble, allowing uncomplicated workup after delivery of Rt to the desired electrophile.2

Alkyl-Transferable Groups.

The first reported applications of the HMPT complex involved addition of alkyllithiums to the complex, forming in situ mixed lithioorganocuprates which alkylated cyclohexenone in excellent yield and chemoselectivity (eq 1).2

Since this initial report, general application in synthesis has been widespread, reflecting the importance of such transformations3-5 (see also 3,3-Dimethyl-1-butynylcopper(I), 1-Hexynylcopper(I), and (3-Methoxy-3-methyl-1-butynyl)copper(I)). It has been shown that in situ generation of the Rt group, by way of its lithio derivative using sonication methods, can result in superior yields of 1,4-addition products.4 A representative example of a complex alkyl Rt is displayed in a synthesis of ceroplastol I (eq 2).5

Alkenyl-Transferable Groups.

The numerous applications of this transformation underline its strategic importance in the synthesis of many natural product systems.6-13 Perhaps the most widely celebrated uses of lithiovinyl-pentynylcuprates have been in the synthesis of prostaglandins and their derivatives.9-12 Vinylogous organocuprates have also been used to construct the framework of prostaglandin endoperoxides (eq 3),6 again highlighting chemoselectivity and efficiency. Chemoselectivity has also been observed in the vinylation of alkyl iodides.7 One-pot conjugate addition-enolate alkylation procedures have been reported, giving moderate yields of the functionalized products (eq 4).8

1. (a) Normant, J. F. S 1972, 63. (b) Sladkov, A. M.; Gol'ding, I. R. RCR 1979, 48, 868. (c) Lipshutz, B. H.; Sengupta, S. OR 1992, 41, 135. (d) FF 1984, 11, 370.
2. Corey, E. J.; Beames, D. J. JACS 1972, 94, 7210.
3. Batten, R. J.; Coyle, J. D.; Taylor, R. J. K. S 1980, 910.
4. Luche, J. L.; Pétrier, C.; Gemal, A. L.; Zikra, N. JOC 1982, 47, 3805.
5. Boeckman, R. K., Jr.; Arvanitis, A.; Voss, M. E. JACS 1989, 111, 2737.
6. Corey, E. J.; Shibasaki, M.; Nicolaou, K. C.; Malmsten, C. L.; Samuelsson, B. TL 1976, 737.
7. Corey, E. J.; Ulrich, P.; Fitzpatrick, J. M. JACS 1976, 98, 222.
8. Cook, S.; Henderson, D.; Richardson, K. A.; Taylor, R. J. K.; Saunders, J.; Strange, P. G. JCS(P1) 1987, 1825.
9. Corey, E. J.; Wollenberg, R. H. JOC 1975, 40, 2265.
10. Salomon, R. G.; Jirousek, M. R.; Ghosh, S.; Sharma, R. B. Prostaglandins 1987, 34, 643.
11. Collins, P. W.; Gasiecki, A. F.; Perkins, W. E.; Gullikson, G. W.; Bianchi, R. G.; Kramer, S. W.; Ng, J. S.; Yonan, E. E.; Swenton, L.; Jones, P. H.; Bauer, R. F. JMC 1990, 33, 2784 and references cited within.
12. Buckler, R. T.; Garling, D. L. TL 1978, 2257.
13. Tanaka, T.; Okamura, N.; Bannai, K.; Hazato, A.; Sugiura, S.; Tomimori, K.; Manabe, K.; Kurozumi, S. T 1986, 42, 6747.

Graham B. Jones & Brant J. Chapman

Clemson University, SC, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.