4-Quinolone 2-methyl-, ring synthesis

Another common use of carbopalladation is to effect a net annelation by side chain installation followed by cyclization. One example from the synthesis of a protected form of the 2-quinolone portion of streptonigrin 40 begins with iodide 37 (Scheme Heck reaction of this electron-rich fully substituted aryl iodide 37 with methyl acrylate provides the substimtion product 38. Extended reflux of 38 under acidic conditions promotes double deprotection, isomerization, and cyclization reaction yielding enamide 39. Another example from the synthesis of ( )-aurantioclavine 41 involves coupling of aryl bromide Standard Heck conditions provide the substitution product 43 in excellent yield at the appropriate oxidation state for cyclization to form the azepine ring en route to the natural product... 

---