A facile and improved route for the synthesis of the orally active spiroindoline-based growth hormone secretagogue, MK-677 was described. The key step adopted the Fischer indole/reduction strategy. The preparation of the key intermediates N-protected piperidine carboxaldehyde 5 and the N-Boc-O-benzyl-D-serine （2） are also optimized.
Xian Liang Qi Er Qun Yang Jun Tao Zhang Tao Wang Xiao Ping Cao
