Synthesis of new nucleoside analogues comprising a methylenecyclobutane unit
摘要:
Synthesis of eight nucleoside analogues 3-10 with a methylene cyclobutane unit is described. Wittig or Peterson reactions with protected 2-hydroxycyclobutanones 12 and 13 gave E- and Z-derivatives, respectively. After functional modifications the heterocyclic moieties were introduced via a Mitsunobu reaction either on the lateral chain or on the cycle. When adenine was used in this reaction only the N-9 substitution products were obtained. Removal of the protecting groups provided the target products. (c) 2005 Elsevier Ltd. All rights reserved.
The first total synthesis of (+)-laurencin (1), which is the most representative marine natural product isolated from red algae, is described via intermediates 2–18. Key steps in the synthesis include a facile oxidative preparation of 2, an effective conversion of 9a to 11, and a SmI2-catalyzed elongation reaction of 15, providing 16a.