5-chloro-1,2-dihydropyrimido<5,4-e>-1,2,4-triazine | 91115-01-4

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 二嗪类
• 英文名称: 5-chloro-1,2-dihydropyrimido<5,4-e>-1,2,4-triazine
• 英文别名: 5-chloro-1,2-dihydropyrimido[5,4-e][1,2,4]triazine；5-chloro-1,2(4)-dihydro-pyrimido[5,4-e][1,2,4]triazine；5-Chlor-1,2-dihydro-pyrimido<5,4-e>asymm.-triazin；5-Chlor-1.2-dihydro-pyrimidin<5.4-e>-as-triazin
• CAS: 91115-01-4
• 化学式: C₅H₄ClN₅
• 分子量: 169.573
• InChiKey: GGKFADMOQZGHCS-UHFFFAOYSA-N

物化性质

• 沸点：
  351.9±52.0 °C(Predicted)
• 密度：
  1.91±0.1 g/cm3(Predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  1.6
• 重原子数：
  11
• 可旋转键数：
  0
• 环数：
  2.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  62.2
• 氢给体数：
  2
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  5-chloro-1,2-dihydropyrimido<5,4-e>-1,2,4-triazine 在 溴 作用下， 以 乙醇 、 水 为溶剂， 反应 21.0h， 生成 6-氨基-1,2,4-三嗪-5-羧酸乙酯
  参考文献：
  名称：

  [EN] FUNGICIDES BASED ON NITROGEN-CONTAINING HETEROCYCLES
  [FR] FONGICIDES A BASE D'HETEROCYCLES CONTENANT DE L'AZOTE

  摘要：

  具有通式（1）的杀真菌化合物：式（1）其中W，Z和X和Y中的另一个是N，另一个是CR8；R8是H，卤素，C1-4烷基，C1-4烷氧基，C1-4烷基硫基或卤代（C1-4）烷基；R和R2独立地是H，卤素，C1-8烷基，C1-8烷氧基，C1-8烷基硫基，C2-8烯基，C2-8炔基，氰基或NR3R4，但至少其中之一是NR3R4；R1是卤素，C1-8烷基，C2-8烯基，C2-8炔基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，C1-8烷氧基，C1-8烷基硫基，芳基，芳氧基，芳硫基，杂芳基，杂芳氧基，杂芳硫基，芳基（C1-4）烷基，芳基（C1-4）烷氧基，杂芳基（C1-4）烷基，杂芳基（C1-4）烷氧基，芳基（C1-4）烷基硫基，杂芳基（C1-4）烷基硫基，吗啉基，哌啶基或吡咯啉基；R3和R4独立地是H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，杂芳基，杂芳基（C1-8）-烷基，NR5R6，但不是R3和R4都是H或NR5R6，或R3和R4一起形成一个C3-7烷基或C3-7烯基链，可选择地用一个或多个C1-4烷基或C1-4烷氧基取代，或与它们所连接的氮原子一起，R3和R4形成吗啉，硫吗啉，硫吗啉S-氧化物或硫吗啉S-二氧化物环或哌嗪或哌嗪N-（C1-4）烷基（特别是N-甲基）环；R5和R6独立地是H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，杂芳基或杂芳基（C1-8）-烷基；任何上述烷基，烯基，炔基或环烷基基团（R8除外）可选择地用卤素，氰基，C1-6烷氧基，C1-6烷基羰基，C1-6烷氧羰基，C1-6卤代烷氧基，C1-6烷基硫基，三（C1-4）烷基硅烷基，C1-6烷基氨基或C1-6二烷基氨基取代，上述任何吗啉，硫吗啉，哌啶，哌嗪和吡咯啉环可选择地用C1-4烷基（特别是甲基）取代，上述任何芳基或杂芳基基团可选择地用一个或多个取代基取代，所述取代基选择自卤素，羟基，硫醇基，C1-6烷基，C2-6烯基，C2-6炔基，C1-6烷氧基，C2-6烯氧基，C2-6炔氧基，卤代（C1-6）烷基，卤代（C1-6）烷氧基，C1-6烷基硫基，卤代（C1-6）烷基硫基，羟基（C1-6）烷基，C1-4烷氧基（C1-6）烷基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯氧基，苄氧基，苯甲酰氧基，氰基，异氰酸基，硫氰酸基，异硫氰酸基，硝基，-NR''R''，NHCOR''，-NHCONR''R''，-CONR''R''，-SO2R''，-OSO2R''，-COR''，-CR''=NR''或-N=CR''R''，其中R''和R''独立地是氢，C1-4烷基，卤代（C1-4）烷基，C1-4烷氧基，卤代（C1-4）烷氧基，C1-4烷基硫基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯基或苄基，苯基和苄基可选择地用卤素，C1-4烷基或C1-4烷氧基取代。

  公开号：

  WO2004056829A1
• 作为产物：
  描述：

  原甲酸三乙酯 、 4-氯-5-氨基-6-肼基嘧啶 在 盐酸 作用下， 以71%的产率得到5-chloro-1,2-dihydropyrimido<5,4-e>-1,2,4-triazine
  参考文献：
  名称：

  吡啶并[3,2- e ] [1,2,4]三嗪的Niementowski型合成：吡啶并[2,3- b ]吡嗪杀真菌剂的强氮杂类似物

  摘要：

  已发现新型三取代的吡啶并[3,2- e ] [1,2,4]三嗪具有与相应的吡并吡嗪杀真菌剂相似的针对重要植物病原体的生物学活性，例如重要的致病性小麦霉菌（Mycosphaerella graminicola）（小麦叶片斑点病），稻瘟病菌（Magnaporthe grisea）（稻瘟病）。以及茄枯萎病（Rhizoctonia solani）。它们是由Niementowski型环缩合首次由单环三嗪制备的。

  DOI：

  10.1016/j.tetlet.2010.03.032

文献信息

• [EN] INHIBITORS OF CELLULAR METABOLIC PROCESSES<br/>[FR] INHIBITEURS DE PROCESSUS MÉTABOLIQUES CELLULAIRES
  申请人：AGIOS PHARMACEUTICALS INC

  公开号：WO2018039972A1

  公开（公告）日：2018-03-08

  The invention provides inhibitor compounds of MAT2A that are useful as therapeutic agents for treating malignancies wherein the compounds have the general formula (I) : wherein ring A, ring B, ring C and, R1 are as described herein.

  该发明提供了MAT2A的抑制剂化合物，可作为治疗恶性肿瘤的治疗剂。这些化合物具有一般公式(I)：其中环A、环B、环C和R1如本文所述。
• Fungicides based on nitrogen-containing heterocycles
  申请人：Crowley Jelf Patrick

  公开号：US20060100203A1

  公开（公告）日：2006-05-11

  Fungicidal compounds having the general formula (1): formula (1) wherein W, Z and one of X and Y are N and the other one of X and Y is CR 8 ; R 8 is H, halo, C 1-4 alkyl, C 1-4 alkoxy, C 1-4 alkylthio or halo(C 1-4 )alkyl; R and R 2 are independently H, halo, C 1-8 alkyl, C 1-8 alkoxy, C 1-8 alkylthio, C 2-8 alkenyl, C 2-8 alkynyl, cyano or NR 3 R 4 , provided that at least one of R and R 2 is NR 3 R 4 ; R 1 is halo, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 alkynyl, C 3-8 cycloalkyl, C 3-8 cycloalkyl(C 1-6 )-alkyl, C 1-8 alkoxy, C 1-8 alkylthio, aryl, aryloxy, arylthio, heteroaryl, heteroaryloxy, heteroarylthio, aryl(C 1-4 )alkyl, aryl(C 1-4 )alkoxy, heteroaryl(C 1-4 )alkyl, heteroaryl(C 1-4 )alkoxy, aryl(C 1-4 )alkylthio, heteroaryl(C 1-4 )alkylthio, morpholino, piperidino or pyrrolidino; R 3 and R 4 are independently H, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 alkynyl, aryl, aryl(C 1-8 )-alkyl, C 3-8 cycloalkyl, C 3-8 cycloalkyl(C 1-6 )alkyl, heteroaryl, heteroaryl(C 1-8 )alkyl, NR 5 R 6 , provided that not both R 3 and R 4 are H or NR 5 R 6 , or R 3 and R 4 together form a C 3-7 alkylene or C 3-7 alkenylene chain optionally substituted with one or more C 1-4 alkyl or C 1-4 alkoxy groups, or, together with the nitrogen atom to which they are attached, R 3 and R 4 form a morpholine, thiomorpholine, thiomorpholine S-oxide or thiomorpholine S-dioxide ring or a piperazine or piperazine N-(C 1-4 )alkyl (especially N-methyl) ring; and R 5 and R 6 are independently H, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 -alkynyl, aryl, aryl(C 1-8 )alkyl, C 3-8 cycloalkyl, C 3-8 cycloalkyl(C 1-6 )alkyl, heteroaryl or heteroaryl(C 1-8 )alkyl; any of the foregoing alkyl, alkenyl, alkynyl or cycloalkyl groups or moieties (other than for R 8 ) being optionally substituted with halogen, cyano, C 1-6 alkoxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 haloalkoxy, C 1-6 alkylthio, tri(C 1-4 )alkylsilyl, C 1-6 alkylamino or C 1-6 dialkylamino, any of the foregoing morpholine, thiomopholine, piperidine, piperazine and pyrrolidine rings being optionally substituted with C 1-4 alkyl (especially methyl), and any of the foregoing aryl or heteroaryl groups or moieties being optionally substituted with one or more substituents selected from halo, hydroxy, mercapto, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-6 alkoxy, C 2-6 alkenyloxy, C 2-6 alkynyloxy, halo(C 1-6 )alkyl, halo(C 1-6 )alkoxy, C 1-6 alkylthio, halo(C 1-6 )alkylthio, hydroxy(C 1-6 )alkyl, C 1-4 alkoxy(C 1-6 )alkyl, C 3-6 cycloalkyl, C 3-6 cycloalkyl(C 1-4 )alkyl, phenoxy, benzyloxy, benzoyloxy, cyano, isocyano, thiocyanato, isothiocyanato, nitro, —NR″′R″″, NHCOR″′, —NHCONR″′R″″, —CONR″′R″″, —SO 2 R″′, —OSO 2 R″′, —COR″′, —CR″′═NR″″ or —N═CR ″′R″″, in which R″′ and R″″ are independently hydrogen, C 1-4 alkyl, halo(C 1-4 )alkyl, C 1-4 alkoxy, halo(C 1-4 )alkoxy, C 1-4 alkylthio, C 3-6 cycloalkyl, C 3-6 cycloalkyl(C 1-4 )alkyl, phenyl or benzyl, the phenyl and benzyl groups being optionally substituted with halogen, C 1-4 alkyl or C 1-4 alkoxy.

  具有通式（1）的杀菌化合物：通式（1）其中，W，Z和X和Y中的另一个是CR8，另一个是N；R8为H，卤素，C1-4烷基，C1-4烷氧基，C1-4烷硫基或卤素（C1-4）烷基；R和R2独立地为H，卤素，C1-8烷基，C1-8烷氧基，C1-8烷硫基，C2-8烯基，C2-8炔基，氰基或NR3R4，但其中至少一个为NR3R4；R1为卤素，C1-8烷基，C2-8烯基，C2-8炔基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，C1-8烷氧基，C1-8烷硫基，芳基，芳氧基，芳硫基，杂环芳基，杂环芳氧基，杂环芳硫基，芳基（C1-4）烷基，芳基（C1-4）烷氧基，杂环芳基（C1-4）烷基，杂环芳基（C1-4）烷氧基，芳基（C1-4）烷硫基，杂环芳基（C1-4）烷硫基，吗啉基，哌啶基或吡咯烷基；R3和R4独立地为H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）烷基，杂环芳基，杂环芳基（C1-8）烷基，NR5R6，但不是R3和R4都为H或NR5R6，或者R3和R4一起形成一个C3-7烷基或C3-7烯基链，可选择地取代一个或多个C1-4烷基或C1-4烷氧基，或者与它们所附着的氮原子一起，R3和R4形成吗啉，硫代吗啉，硫代吗啉S-氧化物或硫代吗啉S-二氧化物环或哌嗪或哌嗪N-（C1-4）烷基（特别是N-甲基）环；R5和R6独立地为H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）烷基，杂环芳基或杂环芳基（C1-8）烷基；除R8之外的任何上述烷基，烯基，炔基或环烷基基团（均可选择地取代卤素，氰基，C1-6烷氧基，C1-6烷基羰基，C1-6烷氧羰基，C1-6卤烷氧基，C1-6烷硫基，三（C1-4）烷基硅烷基，C1-6烷基氨基或C1-6二烷基氨基），任何上述吗啉，硫代吗啉，哌嗪，哌嗪和吡咯烷环可选择地取代C1-4烷基（特别是甲基），任何上述芳基或杂环芳基基团可选择地取代一个或多个取代基，所述取代基选自卤素，羟基，巯基，C1-6烷基，C2-6烯基，C2-6炔基，C1-6烷氧基，C2-6烯氧基，C2-6炔氧基，卤素（C1-6）烷基，卤素（C1-6）烷氧基，C1-6烷硫基，卤素（C1-6）烷硫基，羟基（C1-6）烷基，C1-4烷氧基（C1-6）烷基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯氧基，苄氧基，苯甲酰氧基，氰基，异氰基，硫氰酸基，异硫氰酸基，硝基，—NR″′R″″，NHCOR″′，—NHCONR″′R″″，—CONR″′R″″，—SO2R″′，—OSO2R″′，—COR″′，—CR″′═NR″″或—N═CR″′R″″，其中R″′和R″″独立地为氢，C1-4烷基，卤素（C1-4）烷基，C1-4烷氧基，卤素（C1-4）烷氧基，C1-4烷硫基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯基或苄基，苯基和苄基可选择地取代卤素，C1-4烷基或C1-4烷氧基。
• FUNGICIDES BASED ON NITROGEN-CONTAINING HETEROCYCLES
  申请人：Syngenta Limited

  公开号：EP1575956A1

  公开（公告）日：2005-09-21
• Niementowski-type synthesis of pyrido[3,2-e][1,2,4]triazines: potent aza-analogs of pyrido[2,3-b]pyrazine fungicides
  作者：Patrick J. Crowley、Clemens Lamberth、Urs Müller、Sebastian Wendeborn、Olivia-A. Sageot、John Williams、Alexander Bartovič

  DOI：10.1016/j.tetlet.2010.03.032

  日期：2010.5

  Novel trisubstituted pyrido[3,2-e][1,2,4]triazines have been found to possess similar biological activity to the corresponding pyridopyrazine fungicides against important phytopathogens such as Mycosphaerella graminicola (wheat leaf blotch), Magnaporthe grisea (rice blast), and Rhizoctonia solani (rice sheath blight). They have been prepared for the first time from a monocyclic triazine by Niementowski-type

  已发现新型三取代的吡啶并[3,2- e ] [1,2,4]三嗪具有与相应的吡并吡嗪杀真菌剂相似的针对重要植物病原体的生物学活性，例如重要的致病性小麦霉菌（Mycosphaerella graminicola）（小麦叶片斑点病），稻瘟病菌（Magnaporthe grisea）（稻瘟病）。以及茄枯萎病（Rhizoctonia solani）。它们是由Niementowski型环缩合首次由单环三嗪制备的。
• [EN] FUNGICIDES BASED ON NITROGEN-CONTAINING HETEROCYCLES<br/>[FR] FONGICIDES A BASE D'HETEROCYCLES CONTENANT DE L'AZOTE
  申请人：SYNGENTA LTD

  公开号：WO2004056829A1

  公开（公告）日：2004-07-08

  Fungicidal compounds having the general formula (1): formula (1) wherein W, Z and one of X and Y are N and the other one of X and Y is CR8; R8 is H, halo, C1-4 alkyl, C1-4 alkoxy, C1-4 alkylthio or halo(C1-4)alkyl; R and R2 are independently H, halo, C1-8 alkyl, C1-8 alkoxy, C1-8 alkylthio, C2-8 alkenyl, C2-8 alkynyl, cyano or NR3R4, provided that at least one of R and R2 is NR3R4; R1 is halo, C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, C3-8 cycloalkyl, C3-8 cycloalkyl(C1-6)­-alkyl, C1-8 alkoxy, C1-8 alkylthio, aryl, aryloxy, arylthio, heteroaryl, heteroaryloxy, heteroarylthio, aryl(C1-4)alkyl, aryl(C1-4)alkoxy, heteroaryl(C1-4)alkyl, heteroaryl­(C1-4)alkoxy, aryl(C1-4)alkylthio, heteroaryl(C1-4)alkylthio, morpholino, piperidino or pyrrolidino; R3 and R4 are independently H, C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, aryl, aryl(C1-8)­- alkyl, C3-8 cycloalkyl, C3-8 cycloalkyl(C1-6)alkyl, heteroaryl, heteroaryl(C1-8)alkyl, NR5R6, provided that not both R3 and R4 are H or NR5R6, or R3 and R4 together form a C3-7 alkylene or C3-7 alkenylene chain optionally substituted with one or more C1-4 alkyl or C1-4 alkoxy groups, or, together with the nitrogen atom to which they are attached, R3 and R4 form a morpholine, thiomorpholine, thiomorpholine S-oxide or thiomorpholine S-dioxide ring or a piperazine or piperazine N-(C1-4)alkyl (especially N-methyl) ring; and R5 and R6 are independently H, C1-8 alkyl, C2-8 alkenyl, C2-8 alkynyl, aryl, aryl(C1-8)­alkyl, C3-8 cycloalkyl, C3-8 cycloalkyl(C1-6)alkyl, heteroaryl or heteroaryl(C1-8)alkyl; any of the foregoing alkyl, alkenyl, alkynyl or cycloalkyl groups or moieties (other than for R8) being optionally substituted with halogen, cyano, C1-6 alkoxy, C1-6 alkylcarbonyl, C1-6 alkoxycarbonyl, C1-6 haloalkoxy, C1-6 alkylthio, tri(C1-4)alkylsilyl, C1-6 alkylamino or C1-6 dialkylamino, any of the foregoing morpholine, thiomorpholine, piperidine, piperazine and pyrrolidine rings being optionally substituted with C1-4 alkyl (especially methyl), and any of the foregoing aryl or heteroaryl groups or moieties being optionally substituted with one or more substituents selected from halo, hydroxy, mercapto, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-6 alkoxy, C2-6 alkenyloxy, C2-6 alkynyloxy, halo(C1-6)alkyl, halo(C1-6)alkoxy, C1-6 alkylthio, halo(C1-6)alkylthio, hydroxy(C1-6)alkyl, C1-4 alkoxy(C1-6)alkyl, C3-6 cycloalkyl, C3-6 cycloalkyl(C1-4)alkyl, phenoxy, benzyloxy, benzoyloxy, cyano, isocyano, thiocyanato, isothiocyanato, nitro, -NR''R'', NHCOR'', -NHCONR''R'', -CONR''R'', -SO2R'', -OSO2R'', -COR'', -CR''=NR'' or -N=CR ''R'', in which R'' and R'' are independently hydrogen, C1-4 alkyl, halo-(C1-4)alkyl, C1-4 alkoxy, halo(C1-4)alkoxy, C1-4 alkylthio, C3-6 cycloalkyl, C3-6 cycloalkyl(C1-4)alkyl, phenyl or benzyl, the phenyl and benzyl groups being optionally substituted with halogen, C1-4 alkyl or C1-4 alkoxy.

  具有通式（1）的杀真菌化合物：式（1）其中W，Z和X和Y中的另一个是N，另一个是CR8；R8是H，卤素，C1-4烷基，C1-4烷氧基，C1-4烷基硫基或卤代（C1-4）烷基；R和R2独立地是H，卤素，C1-8烷基，C1-8烷氧基，C1-8烷基硫基，C2-8烯基，C2-8炔基，氰基或NR3R4，但至少其中之一是NR3R4；R1是卤素，C1-8烷基，C2-8烯基，C2-8炔基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，C1-8烷氧基，C1-8烷基硫基，芳基，芳氧基，芳硫基，杂芳基，杂芳氧基，杂芳硫基，芳基（C1-4）烷基，芳基（C1-4）烷氧基，杂芳基（C1-4）烷基，杂芳基（C1-4）烷氧基，芳基（C1-4）烷基硫基，杂芳基（C1-4）烷基硫基，吗啉基，哌啶基或吡咯啉基；R3和R4独立地是H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，杂芳基，杂芳基（C1-8）-烷基，NR5R6，但不是R3和R4都是H或NR5R6，或R3和R4一起形成一个C3-7烷基或C3-7烯基链，可选择地用一个或多个C1-4烷基或C1-4烷氧基取代，或与它们所连接的氮原子一起，R3和R4形成吗啉，硫吗啉，硫吗啉S-氧化物或硫吗啉S-二氧化物环或哌嗪或哌嗪N-（C1-4）烷基（特别是N-甲基）环；R5和R6独立地是H，C1-8烷基，C2-8烯基，C2-8炔基，芳基，芳基（C1-8）-烷基，C3-8环烷基，C3-8环烷基（C1-6）-烷基，杂芳基或杂芳基（C1-8）-烷基；任何上述烷基，烯基，炔基或环烷基基团（R8除外）可选择地用卤素，氰基，C1-6烷氧基，C1-6烷基羰基，C1-6烷氧羰基，C1-6卤代烷氧基，C1-6烷基硫基，三（C1-4）烷基硅烷基，C1-6烷基氨基或C1-6二烷基氨基取代，上述任何吗啉，硫吗啉，哌啶，哌嗪和吡咯啉环可选择地用C1-4烷基（特别是甲基）取代，上述任何芳基或杂芳基基团可选择地用一个或多个取代基取代，所述取代基选择自卤素，羟基，硫醇基，C1-6烷基，C2-6烯基，C2-6炔基，C1-6烷氧基，C2-6烯氧基，C2-6炔氧基，卤代（C1-6）烷基，卤代（C1-6）烷氧基，C1-6烷基硫基，卤代（C1-6）烷基硫基，羟基（C1-6）烷基，C1-4烷氧基（C1-6）烷基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯氧基，苄氧基，苯甲酰氧基，氰基，异氰酸基，硫氰酸基，异硫氰酸基，硝基，-NR''R''，NHCOR''，-NHCONR''R''，-CONR''R''，-SO2R''，-OSO2R''，-COR''，-CR''=NR''或-N=CR''R''，其中R''和R''独立地是氢，C1-4烷基，卤代（C1-4）烷基，C1-4烷氧基，卤代（C1-4）烷氧基，C1-4烷基硫基，C3-6环烷基，C3-6环烷基（C1-4）烷基，苯基或苄基，苯基和苄基可选择地用卤素，C1-4烷基或C1-4烷氧基取代。