螺旋雙環醚及內酯的新合成方法

Abstract

我們利用本實驗室常用的鋅銅試劑製備出共軛3-(2-酯烴)環己烯酮，在-78 ℃與二異丁基鋁反應後、以6N鹽酸終止反應可得1-氧螺[4.5]癸-6-烯。以相同條件將共軛3-(3-酯烴)環己烯酮進行環化反應可得1-氧螺[5.5]十一-7-烯；共軛3-(2-酯烴)環戊烯酮進行環化反應可得1-氧螺[4.4]壬-6-烯；而共軛3-(3-酯烴)環戊烯酮進行環化反應可得6-氧螺[4.5]癸-1-烯。 共軛3-(2-羧酸)環己烯酮，是以共軛3-(2-酯烴)環己烯酮經由氫氧化鉀進行酸水解而得，在0 ℃與硼氫化鈉反應後、以6N鹽酸終止反應可得1-氧螺[4.5]癸-6-烯-2-酮。利用相同條件將共軛3-(2-羧酸)環戊烯酮進行環化反應可得1-氧螺[4.4]癸-6-烯-2-酮。 有許多已知的天然物成分都含有異核原子或是螺旋結構，而我們由環化反應得到的螺旋雙環醚及螺旋雙環內酯仍保留了一個雙鍵，可以用來作為官能基的延伸，或是經由多步反應進行天然物的全合成。

The allylic oxaspirocyclic products obtained have a structure very similar to naturally occurring norisoprenoid spiroethers, such as theaspiranes and vetispirane, which are known aroma components in tea and vanilla, respectively. We have successfully synthesized oxa-spiro compounds by addition of diisobutylaluminum hydride (DIBAL) to cyclohex-2-en-1-one bearing an ester-group side chain at C-3 position. The reaction may proceed through an intermediate such as diol. Spiro [5.4] oxadecane was isolated by treating of diol with 6N HCl(aq). Under the same reaction conditions, spiro [5.5] oxaundecane, spiro [4.4] oxanonanes and spiro [5.4] oxadecane were obtained in good yields. Then we extend this chemistry to spiro compounds containing a lactone moiety. Treatment of starting acid with either DIBAL or NaBH4 would generate allylic alcohol intermediate with an acid functionality at the C-3 position. Treatment of 6N HCl would produce an allylic cation which can undergo addition by the carboxy group to furnish spirolactone. Under the reaction conditions, 1-oxaspiro[4.5]dec-6-en-2-one, 1-oxaspiro[4.4]non-6-en-2-one, 3,4,6,7,8,8a-hexahydro-2H-chromen-2-one were obtained.