Cuprous bromide-dimethyl sulfide complex

The jacketed addition funnel is removed and 1.5 g of cuprous bromide-dimethyl sulfide complex (Note 7) is added through a powder funnel. A 500-mL, pressure-equalizing addition funnel (long-tipped) is attached to the flask and flushed with argon. As the anion solution is cooled in a dry ice-isopropyl alcohol bath, a solution of 530 g (2.08 mol) of sublimed iodine in 500 mL of anhydrous tetrahydrofuran is placed in the addition funnel. This solution is added dropwise to the cooled slurry over approximately 90 min (Note 8). The solution is stirred for about 15 min at low temperature. 

Cuprous bromide/dimethyl sulfide complex was purchased from Aldrich Chemical Company, Inc. and used as such. 

Dehydroprogesterone (1) was purchased from Sigma Chemical Company and used without further purification. Cuprous bromide-dimethyl sulfide complex was prepared according to House s procedure.2 Hexamethyl-phosphoramide, chlorotrimethylsilane, and triethylamine were purchased from Tokyo Kasei Kogyo Co., Ltd., Japan and distilled from calcium hydride (CaH2>. Tetrahydrofuran (THF) was distilled from sodium-benzophenone ketyl immediately prior to use. Methylene chloride was distilled from phosphorus pentoxide (P2O5). 

Cuprous bromide/dimethyl sulfide (54678-23-8), 66, 51 Cuprous chloride-pyridine complex, 66, 182 [2 + 2] CYCLOADDmON, 65, 135... 

However, the related cuprate reagent (3), prepared from 2-lithio-3,3-diethoxy-propene and the dimethyl sulfide complex of cuprous bromide, undergoes... 

In their stereorational synthesis of (+)-[10.10] 61b, they reacted the epoxide 107 with a 1 1 3-butenylmagnesium bromide-cuprous iodide complex in dimethyl-sulfide-THF at low temperature. The predominant SN2 pathway gave the (+)-( )-allyl alcohol 108 whose Sharpless asymmetric epoxidation in dichloromethane at —23 °C for 10 min provided the corresponding epoxy alcohol and recovered (+)-(R)-allyl alcohol 108 (78 % yield and 95 % optical purity). The (R)-configuration was assigned following the Sharpless model61 for allylic alcohol epoxidation. 

This complex is prepared from cuprous bromide and dimethyl sulfide according to the procedure of House. The complex must be pure white. Slightly Impure samples will produce pinkish solutions which are unsatisfactory for this procedure. Normally, the complex is dark red when it is first prepared, but the required state of purity can be achieved by two or three recrystallizations under a nitrogen atmosphere as described by House.2 We have found, however, that if the Initially-formed complex has a distinctly green appearance, it cannot be purified satisfactorily. Others have also been concerned about this matter of purification. 

Vinyl halides. The method of Normant et al. (6, 270) for preparation of vinylcopper compounds can be used to obtain vinyl halides. Reaction of 1 with iodine gives vinyl iodides directly, but this reaction when extended to Bf2 or CI2 gives mainly dimers. The desired vinyl chlorides and bromides canTte obtained with NCS or NBS in fair to good yields. The replacement occurs with retention of initial stereochemistry. The American group also stresses the importance of the purity of the copper salt and uses House s cuprous bromide complex with dimethyl sulfide (6, 270). 

This complex 1s prepared from cuprous bromide and dimethyl sulfide... 

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