Copper(I) Iodide-Trimethyl Phosphite


[34836-53-8]  · C3H9CuIO3P  · Copper(I) Iodide-Trimethyl Phosphite  · (MW 314.52)

(promoter for the decomposition of diazo ketones and esters and for conjugate addition of alkyl (vinyl, etc.) lithium reagents to a,b-unsaturated ketones and related compounds)

Physical Data: mp 192-193 °C.1

Solubility: sol warm methanol, ethyl acetate, acetone, aniline, and dimethylaniline; also sol aq ammonia.

Form Supplied in: white crystalline powder (98%). Drying: dried at 60 °C (1 mmHg) for 12 h.

Purification: recrystallized from acetone or chloroform.

Analysis of Reagent Purity: recrystallization to constant mp and elemental analysis.

Handling, Storage, and Precautions: irritant; use in a fume hood; mechanical exhaust required; harmful by inhalation, ingestion or skin absorption; incompatible with strong oxidizing agents; sensitive to air, moisture, and light; store under N2 in a cool dry place.

Decomposition of Diazo Ketones and Diazo Esters.

Along with other copper(I) salts, copper(I) iodide-trimethyl phosphite has been utilized to promote the decomposition of a-diazoacetophenone in cyclohexene to the mixture of insertion products shown in eq 1, with overall yields less than 50% and with the cyclopropane derivative produced in amounts at least six times that of the others.1

Indeed, decomposition of diazoacetic and diazomalonic esters in the presence of copper(I) iodide-trimethyl phosphite appears to be the method of choice.2 The decomposition of diazomalonates in the presence of 1,2-ethylenedithiolato metallocene complexes is reported to be accelerated by CuI-P(OMe)3.3,4 It has also been reported that the intramolecular cyclization of the presumed carbonyl ylides derived from diazoacetates produces furanones directly (eq 2),5,6 or the corresponding reaction products with alkenes.7,8 Diethyl diazomalonate, in ethanol and in the presence of the copper(I) iodide-trimethyl phosphite reagent, permitted insertion into the hydroxyl group of the solvent to produce diethyl ethoxymalonate (82%) and a small amount (12%) of tetraethyl ethylenetetracarboxylate.9

Conjugate Addition.

The copper(I) iodide-trimethyl phosphite/lithium dimethylcuprate complex has been compared with the corresponding Tri-n-butylphosphine complex of Copper(I) Iodide and Lithium Dimethylcuprate in the addition reactions to 5-methyl-2-cyclohexenone (eq 3), 3-methyl-2-cyclohexenone (eq 4), and 5,5-dimethyl-2-cyclohexenone (eq 5).10

For the first case (eq 3), both reagents gave predominately trans product (trans:cis = 98:2), but the reaction with the tri-n-butylphosphine complex produced a 34% yield of products while the trimethyl phosphite complex yielded product in 73-87% (as a function of the amount of Lithium Iodide added or of tertiary phosphine ligand present). In both the second and third cases (eqs 4 and 5) the two complexes gave approximately the same yields.10 Under other circumstances (where the complexes were not isolated but rather generated and used in situ), the relative yields for conjugate addition reactions have been reported to be much diminished for the copper(I) iodide-trimethyl phosphite reagent.11 The same observation was also made with regard to the ring opening reaction of b-propiolactones with various copper reagents.12 Additionally, an early investigation of the attempted preparation of dialkenylcuprates [(CH2=CH)2CuLi] suggested that the use of copper(I) iodide-trimethyl phosphite as the source of copper was only partially successful (as were many others) in avoiding decomposition of the vinyl cuprate.13 Nonetheless, in the presence of Boron Trifluoride Etherate, copper(I) iodide-trimethyl phosphite clearly has a salutary effect on the conjugate addition of the copper reagent derived from lithium N-t-butylvaleraldimine to 2-cyclohexenone.14

Related Reagents.

Copper(I) Iodide-Tributylphosphine; Copper(I) Iodide-Tributyl Phosphite; Copper(I) Iodide-Triethylphosphine-Lithium Naphthalenide; Copper(I) Iodide-Triethyl Phosphite; Lithium Diethylcuprate; Lithium Diethylcuprate-Tributylphosphine.

1. House, H. O.; Fischer, W. F.; Gall, M.; McLaughlin, T. E.; Peet, N. P. JOC 1971, 36, 3429.
2. (a) Peace, B. W.; Wulfman, D. S. TL 1971, 3799. (b) Peace, B. W.; Carman, F.; Wulfman, D. S. S 1971, 658. (c) Wulfman, D. S.; Peace, B. W.; Steffen, E. K. CC 1971, 1360. (d) Peace, B. W.; Wulfman, D. S. S 1973, 137.
3. Sakurada, M.; Kajitani, M.; Dohki, K.; Akiyama, T.; Sugimori, A. JOM 1992, 423, 141.
4. Kajitani, M.; Sakurada, M.; Dohki, K.; Suetsugu, T.; Akiyama, T.; Sugimori, A. CC 1990, 19.
5. Bien, S.; Gillon, A. TL 1974, 3074.
6. Bien, S.; Gillon, A.; Kohen, S. JCS(P1) 1976, 489.
7. Wenkert, E.; Alonso, M. E.; Buckwalter, B. L.; Chou, K. J. JACS 1977, 99, 4778.
8. Kolsaker, P.; Kvarsnes, A.; Storesund, H.-J. Org. Mass Spectrom. 1986, 21, 535.
9. Pellicciari, R.; Cogolli, P. S 1975, 269.
10. House, H. O.; Fischer, W. F. JOC 1968, 33, 949.
11. Suzuki, M.; Suzuki, T.; Kawagishi, T.; Morita, Y.; Noyori, R. Isr. J. Chem. 1984, 24, 118.
12. Kawashima, M.; Sato, T.; Fujisawa, T. T 1989, 45, 403.
13. House, H. O.; Umen, M. J. JOC, 1973, 38, 3893.
14. Ito, Y.; Imai, H.; Matsuura, T.; Saegusa, T. TL 1984, 3091.

Linda M. Mascavage

Beaver College, Glenside, PA, USA

David R. Dalton

Temple University, Philadelphia, PA, USA

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