Bromine, reaction with y-butyrolactone

Bromine, reaction with y-butyrolactone in presence of red phosphorus, 46, 22... 

Bicyclo[2.2.1]hepta-2,5-diene, reaction with acetic acid to yield nortii-cyclyl acetate, 46, 74 Bicj clohexyl, 45, 61 2-Biphenylylmagnesium iodide, 46, 94 Bomyl chloride 46, 56 Bromination of y-butyrolactone, 46, 22 Bromine, reaction with i-butyrolactone in presence of red phosphorus, 46, 22... 

Method Three, Livak et ad. (521). a-Bromo-y-butyrolactone (A) is prepared in 80% yield from y-butyrolactone (commercial avmlable), FBr, and bromine. a-Amino-y-hydroxybutyric acid (B) is prepared in 60% yield by amination of (A). 5-()8-Bromoethyl)-hydantoin (C) is prepared in 51% yield by the reaction of (B) with potassium cyanate to give y-hydroxy-a-ureidobutyric acid (D) and by the HBr hydrolyris of (D). 5-(j0-Methylmercaptoethyl)-hydantoin (E) is prepared in 73% yield from sodium methylmercaptide and (C). DL-Methionine is prepared in 95% yield by the Ba(OH)j hydrolysis of (E). The over-all yield is about 17%. 

Bromoetheriflcation of aikenes can be achieved using NBS in the desired alcohol as the solvent. The reaction of 1,3-dichloropropene with NBS in methanol yields an a-bromo dimethyl acetal in the first step in a convenient synthesis of cyclopropenone. Using propargyl alcohol the reaction depicted in eq 22 has been extended to an annulation method for the synthesis of a-methylene-y-butyrolactones. Intramolecular bromoetheriflcation and bromoamination reactions are generally very facile (eq 23). In natural products synthesis, bromoetheriflcation has been used for the s)mthesis of cyclic ethers (by subsequent de-bromination, see tributylstannane) and for the protection of alkene appendages as cychc bromoethers (regenerated by reaction with zinc). ... 

Regioselective oxidation of primary, secondary 1,4-dioIs with bromine and a nickel(ii) salt provides y-substituted butyrolactones in good yields. The tetrahydrofuran (104, R = Me) is also oxidized regioselectively with chromic anhydride to the lactone (105) in low yield, but the reaction has been used in the synthesis of compounds related to methylenomycin. However, the... 

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