Gais Hans-Joachim, Reddy Leleti R, Babu Gadamsetti S, Raabe Gerhard
Institut für Organische Chemie der Rheinisch-Westfälischen Technischen Hochschule (RWTH) Aachen, Prof.-Pirlet-Strasse 1, D-52056 Aachen, Germany.
J Am Chem Soc. 2004 Apr 21;126(15):4859-64. doi: 10.1021/ja030501v.
Treatment of the bis(allylsulfoximine)titanium complexes derived from the beta-methyl-substituted acyclic allylic sulfoximines 13a and 13b with aldehydes gave with high selectivities the corresponding sulfoximine-substituted homoallylic alcohols which were isolated as the silyl ethers 15a-h. Methylation of sulfoximines 15a-h afforded the aminosulfoxonium salts 5a-h which upon treatment with LiN(H)tBu gave in high yields the enantio- and diastereomerically pure silyl-substituted 2,3-dihydrofurans 4a-h. Treatment of the titanium complexes derived from the cyclic allylic sulfoximines 17a, 17b, and ent-17c with p-MeOC(6)H(4)CHO delivered with high selectivities the corresponding sulfoximine-substituted cyclic homoallylic alcohols which were isolated as the silyl ethers 18a, 18b, and ent-18c, respectively. Methylation of sulfoximines 18a, 18b, and ent-18c furnished the aminosulfoxonium salts 8a, 8b, and ent-8c, respectively, whose treatment with LiN(H)t-Bu gave the enantio- and diastereomerically pure fused bicyclic 2,3-dihydrofurans 6a, 6b, and ent-6c, respectively, in good yields. It is proposed that the 1-alkenyl aminosulfoxonium salts 5a-h, 8a, 8b, and ent-8c react with the base under alpha-elimination and formation of the acyclic and cyclic beta-silyloxy alkylidene carbenes 2a-h, 7a, 7b, and ent-7c, respectively, which then undergo a 1,5-O,Si-bond insertion and 1,2-silyl migration. The cyclic aminosulfoxonium salts 8a, 8b, and ent-8c upon treatment with 1,8-diazabicyclo[5.4.0]-7-undecene did not undergo an alpha-elimination but suffered a novel migratory cyclization with formation of the enantio- and diastereomerically pure bicyclic tetrahydrofurans 9a, 9b, and ent-9c, respectively. It is proposed that the 1-alkenyl sulfoxonium salts 8a, 8b, and ent-8c are isomerized to the allylic aminosulfoxonium salts 10a, 10b, and ent-10c, respectively, which then suffer an intramolecular substitution of the (dimethylamino)sulfoxonium group by the silyloxy group followed by a desilylation. The syntheses of the 2,3-dihydrofurans 4a-h, 6a, and 6b and of the tetrahydrofurans 9a and 9b are accompanied by the formation of sulfinamide 16 of >or=98% ee, which can be converted via sulfoxide 28 of >or=98% to the starting sulfoximine 11 of >or=98% ee.
用醛处理由β-甲基取代的无环烯丙基亚砜亚胺13a和13b衍生的双（烯丙基亚砜亚胺）钛配合物，以高选择性得到相应的亚砜亚胺取代的高烯丙醇，它们被分离为硅醚15a - h。亚砜亚胺15a - h的甲基化得到氨基亚砜鎓盐5a - h，用LiN(H)tBu处理后，以高收率得到对映体和非对映体纯的硅基取代的2,3 - 二氢呋喃4a - h。用对甲氧基苯甲醛处理由环状烯丙基亚砜亚胺17a、17b和对映体-17c衍生的钛配合物，以高选择性得到相应的亚砜亚胺取代的环状高烯丙醇，它们分别被分离为硅醚18a、18b和对映体-18c。亚砜亚胺18a、18b和对映体-18c的甲基化分别得到氨基亚砜鎓盐8a、8b和对映体-8c，用LiN(H)t-Bu处理它们，以良好的收率分别得到对映体和非对映体纯的稠合双环2,3 - 二氢呋喃6a、6b和对映体-6c。有人提出，1 - 烯基氨基亚砜鎓盐5a - h、8a、8b和对映体-8c在α-消除和形成无环和环状β-硅氧基亚烷基卡宾2a - h、7a、7b和对映体-7c的情况下与碱反应，然后它们经历1,5 - O,Si键插入和1,2 - 硅基迁移。用1,8 - 二氮杂双环[5.4.0]-7 - 十一碳烯处理环状氨基亚砜鎓盐8a、8b和对映体-8c时，不会发生α-消除，而是经历一种新颖的迁移环化反应，分别形成对映体和非对映体纯的双环四氢呋喃9a、9b和对映体-9c。有人提出，1 - 烯基亚砜鎓盐8a、8b和对映体-8c分别异构化为烯丙基氨基亚砜鎓盐10a、10b和对映体-10c，然后它们经历（二甲基氨基）亚砜鎓基团被硅氧基进行的分子内取代，随后进行脱硅反应。2,3 - 二氢呋喃4a - h、6a和6b以及四氢呋喃9a和9b的合成伴随着形成ee值≥98%的亚磺酰胺16，其可以通过ee值≥98%的亚砜28转化为ee值≥98%的起始亚砜亚胺11。
