Complex aldol reactions for the construction of dense polyol stereoarrays: synthesis of the C33-C36 region of aflastatin A.
نویسندگان
چکیده
[reaction: see text]. Facial selectivity in the addition of boron enolates of alpha-oxygenated ketones to anti-disposed alpha,beta-bisalkoxy aldehydes is controlled by the aldehyde vicinal diol protecting group. Protection of the diol as an acetonide results in the exclusive formation of the anti-syn-anti stereoarray found in the C(33)-C(36) region of aflastatin A.
منابع مشابه
Synthesis and confirmation of the absolute stereochemistry of the (-)-aflastatin A C9-C27 degradation polyol.
[reaction: see text]. The C(8)-C(18) ethyl ketone and C(19)-C(28) aldehyde aflastatin A fragments were synthesized and coupled using a diastereoselective anti aldol reaction. This adduct was successfully converted into the C(9)-C(27) polyol degradation product of (-)-aflastatin A to confirm the relative and absolute stereochemistry of this region of the natural product.
متن کاملSynthesis of some Polyol Esters and Diesters Catalyzed with SnO2 and Nano-SnO2
Esterification reactions of some polyols and diols were investigated in the presence of SnO2 and nano-SnO2 and the results were compared with the catalyst-free conditions. High conversions were obtained for most of the reactions in the presence of SnO2 and nano-SnO2 which shows the high catalytic activity of SnO2 and nano-SnO2</sub...
متن کاملTwo-step synthesis of carbohydrates by selective aldol reactions.
Studies of carbohydrates have been hampered by the lack of chemical strategies for the expeditious construction and coupling of differentially protected monosaccharides. Here, a synthetic route based on aldol coupling of three aldehydes is presented for the de novo production of polyol differentiated hexoses in only two chemical steps. The dimerization of alpha-oxyaldehydes, catalyzed by l-prol...
متن کاملMicrowave assisted green synthesis of α, ά- bis (substituted- benzylidene) alkanones
Microwave assisted green synthesis of α, ά- bis (substituted- benzylidene) alkanones by the crossed- aldol condensation reaction of substituted aryl aldehydes with ketones in the presence of catalytic amount of NbCl5 in good to excellent yields. This reaction is carried out under solvent-free conditions. The results showed that aldehydes bearing electron–donating substituent's on phenyl-ring fa...
متن کاملOne-pot Synthesis of Polysubstituted Indolizine Derivatives
An efficient approach to the synthesis of 1,2,3-trisubstituted indolizines is described via one-pot reactions of pyridine and dialkyl acetylendicarboxylate in the presence of ethyl 2-chloroacetoacetate in MeOH at room temperature. The corresponding 1, 2, 3-trisubstituted indolizines may be useful building blocks for the construction of complex indolizine derivatives.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Organic letters
دوره 7 15 شماره
صفحات -
تاریخ انتشار 2005