9-(2,3-Dideoxy-β-D-glyceropent-2-enofuranosyl)adenine (2′,3′-didehydro-2′,3′-dideoxyadenosine, 9a), 9-(2,3-dideoxy-β-D-glyceropent-2-enofuranosyl)hypoxanthine (2′,3′-didehydro-2′,3′-dideoxyinosine, 9b) and 4-amino-7-(2,3-dideoxy-β-D-glyceropent-2-enofuranosyl)pyrrolo[2,3-d]pyrimidine (2′,3′-didehydro-2′,3′-dideoxytubercidin, 9c) were prepared via a free radical β-elimination of bromo and phenoxy(thiocarbonyl) leaving groups from appropriate 5′-O-(2-acetoxyisobutyryl)-2′(3′)-phenoxy(thiocarbonyl)-3′(2′)-bromo derivatives 6, 7 of adenosine (1a), inosine (1b) and tubercidin (1c) with tributyltin hydride and subsequent deprotection of the resulting 5′-O-(2-acetoxyisobutyryl)-2′,3′-didehydro-2′,3′-dideoxynucleosides 8a, 8b and 8c, respectively.
通过自由基β-消除反应,从适当的5′-O-(2-乙酰氧异丁酰基)-2′(3′)-苯氧(
硫羰基)-3′(2′)-
溴代衍
生物6、7中去除
溴和苯氧(
硫羰基)离去基团,制备了9-(2,3-二脱氧-β-D-
甘油戊-2-烯
呋喃糖基)
腺苷(2′,3′-二脱氢-2′,3′-二脱氧
腺苷,9a)、9-(2,3-二脱氧-β-D-
甘油戊-2-烯
呋喃糖基)
次黄嘌呤(2′,3′-二脱氢-2′,3′-二脱氧
肌苷,9b)和4-
氨基-7-(2,3-二脱氧-β-D-
甘油戊-2-烯
呋喃糖基)
吡咯并[2,3-d]
嘧啶(2′,3′-二脱氢-2′,3′-二脱氧结核菌素,9c)。这些化合物分别由
腺苷(1a)、
肌苷(1b)和结核菌素(1c)与三
丁基锡氢化物反应,然后分别对得到的5′-O-(2-乙酰氧异丁酰基)-2′,3′-二脱氢-2′,3′-二脱氧核苷8a、8b和8c进行脱保护。