3691Dimethyl oxalate was also observed when the polar material obtained from the ozonolyiiis of 4 (14 mg) was treated in a similar fashion.Reduction of the Enamides 11 and 12 with Sodium Borohydride. To 2 mg of a 1:l mixture of l l and 12 dissolved in 15 mL of ethanol was added 100 mg of sodium borohydride. The solution was stirred at room temperature for 20 h. Excess reagent was destroyed with 1 N hydrochloric acid, and the solution was concentrated and extracted with dichloromethane. The dichloromethane layer was dried over anhydrous sodium sulfate and evaporated to give a mixture of 17 and 18: 'H NMR ((C-DB)&30) 6 1.0 (m, (CHJ2CII), 1.7 (m, Leu -y-CH and P-CH2), 1.78 (s, NHAc), 1.9 (m, Val P-CH), 2.73 (dd, J = 7.5, 15.7 Hz, Trp P-CH2), 2.90 (dd, J = 6.3, 15.7, Trp P-CH,), 3.36 (s, OMe), 3.66 (m, @-CH2), 3.93 (m, Leu a-CH), 4.02 (m, Val a-CH), 4.45 (m, a-CH), 4.73 (m, a-CH), 7.09 (dd, J = 1.6, 8.7 Hz, indole H5), 7.11 (br s, CONH2), 7.13 (d, J = 2.7 Hz, indole H2), 7.54 (d, J = 1.6 Hz, indole H,), 7.56 (d, J = 8.7 Hz, indole H4), 7.80 (d, J = 8.3 Hz, NH), 7.92 (br s, CONHJ, 8.31 (s, PhH), 10.92 (br s, indole Hi).Isolation with Acetic& Anhydride. A small-scale isolation procedure (40 g, wet weight of sponge) employing acetic-d6 anhydride (10 mL, 99+ atom %; Aldrich) as the acetylating agent yielded hexaacetylcelenamide-d18 A (5,12 mg) and hexaacetylcelenamide-d18 B (6,8 mg) which proved to be identical with 3 and 4 (TLC, IR, 'H NMR), respectively, with the exception of the absence of signals in the 'H NMR spectra corresponding to phenol acetate and acetamide.
Acknowledgment. We thank Michael LeBlanc (British
Columbia collections) andBoth R and S phosphorus epimers of menthylmethylphenylphosphine and its phosphine oxide and of neomenthylmethylphenylphosphine and ita phosphine oxide were prepared. The menthylmethylphenylphosphine oxides were prepared from neomenthyldiphenylphosphine by a method which is potentially general for synthesis of phosphines and phosphine oxides having chiral organic groups ligated to chiral phosphorus. Thus, neomenthyldiphen ylphosphine was quaternized by methyl iodide to give neomenthylmethyldiphenylphosphonium iodide which was decomposed in boiling aqueous methanolic sodium hydroxide to give a 1:l mixture of R and S phosphorus epimers of menthylmethylphenylphosphine oxides. The pure diastereomers were obtained from the mixture by fractional crystallization and reduced to the phosphines by using hexachlorodisilane. Structures of the R phosphorus epimers of both menthyl-and neomenthylmethylphenylphosphine oxides are reported. The structure of q4-(1,5-cyclooctadiene)bis[(R)-menthylmethylphenylphosphine]rhodium(I) tetrafluoroborate is also reported.
