The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Miwako Mori - One of the best experts on this subject based on the ideXlab platform.
-
Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...
-
palladium catalyzed asymmetric allylic substitution of 2 arylcyclohexenol derivatives asymmetric total syntheses of crinamine haemanthidine and Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...
Toyoki Nishimata - One of the best experts on this subject based on the ideXlab platform.
-
Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...
-
palladium catalyzed asymmetric allylic substitution of 2 arylcyclohexenol derivatives asymmetric total syntheses of crinamine haemanthidine and Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...
Yongqiang Zhang - One of the best experts on this subject based on the ideXlab platform.
-
a general approach to crinine type amaryllidaceae alkaloids total syntheses of haemanthidine Pretazettine tazettine and crinamine
Tetrahedron, 2006Co-Authors: Fumin Zhang, Yongqiang Tu, Xiangdong Hu, Shaohua Wang, Yongqiang ZhangAbstract:A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-Pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively.
Fumin Zhang - One of the best experts on this subject based on the ideXlab platform.
-
a general approach to crinine type amaryllidaceae alkaloids total syntheses of haemanthidine Pretazettine tazettine and crinamine
Tetrahedron, 2006Co-Authors: Fumin Zhang, Yongqiang Tu, Xiangdong Hu, Shaohua Wang, Yongqiang ZhangAbstract:A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-Pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively.
-
A general approach to crinine-type Amaryllidaceae alkaloids: total syntheses of (±)-haemanthidine, (±)-Pretazettine, (±)-tazettine, and (±)-crinamine
Tetrahedron, 2006Co-Authors: Fumin Zhang, Yongqiang Tu, Shaohua Wang, Xiang‐dong Hu, Yong‐qiang ZhangAbstract:A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-Pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively.
Yoshihiro Sato - One of the best experts on this subject based on the ideXlab platform.
-
Palladium-Catalyzed Asymmetric Allylic Substitution of 2-Arylcyclohexenol Derivatives: Asymmetric Total Syntheses of (+)-Crinamine, (−)-Haemanthidine, and (+)-Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...
-
palladium catalyzed asymmetric allylic substitution of 2 arylcyclohexenol derivatives asymmetric total syntheses of crinamine haemanthidine and Pretazettine
Journal of Organic Chemistry, 2004Co-Authors: Toyoki Nishimata, Yoshihiro Sato, Miwako MoriAbstract:Much interest has been shown in Amaryllidaceae alkaloids as synthetic targets due to their wide range of biological activities. Over 100 alkaloids have been isolated from members of the Amaryllidaceae family; most of them can be classified into eight skeletally homogeneous groups. We have succeeded in the first asymmetric total syntheses of the crinane-type alkaloids (+)-crinamine (1), (−)-haemanthidine (2), and (+)-Pretazettine (3). The starting cyclohexenylamine 14 was obtained from allyl phosphonate 11c by palladium-catalyzed asymmetric amination in 82% yield and with 74% ee. The product was recrystallized from MeOH. Interestingly, (−)-14 with 99% ee was obtained from the mother liquor (74% recovery). Intramolecular carbonyl−ene reaction of (−)-10 proceeds in a highly stereoselective manner to give hexahydroindole derivative 9 as the sole product. In the Lewis-acid-catalyzed carbonyl−ene reaction, an interesting rearrangement product, 20, was isolated in high yield. From 9, (+)-crinamine was synthesize...