364597-58-0Relevant academic research and scientific papers
Total syntheses of pamamycin 607 and methyl nonactate: Stereoselective cyclisation of homoallylic alcohols that had been prepared with remote stereocontrol using allylstannanes
Germay, Olivier,Kumar, Naresh,Moore, Christopher G.,Thomas, Eric J.
, p. 9709 - 9733 (2013/01/16)
The tin(iv) chloride mediated cyclisation of (Z)-homoallylic alcohols using phenylselenenyl chloride or phthalimide in the presence of a Lewis acid followed by reductive removal of the phenylselenenyl group was found to give 2,5-cis-disubstituted tetrahydrofurans with excellent stereocontrol. Using this procedure, (2S,4S,8R,6Z)-9-benzyloxy-2-tert-butyldiphenylsilyloxy-8-methylnon-6- en-4-ol (11), prepared stereoselectively via the tin(iv) chloride promoted reaction between the (R)-5-benzyloxy-4-methylpent-2-enyl(tributyl)stannane (3) and (S)-3-tert-butyldiphenylsilyloxybutanal (10), gave (2S,3R,6S,8S)-1- benzyloxy-8-tert-butyldiphenylsilyloxy-3,6-epoxy-2-methylnonane (13) after deselenation. This tetrahydrofuran was selectively deprotected, oxidized and esterified to give methyl nonactate (2). Having established this synthesis of 2,5-cis-disubstituted tetrahydrofurans, it was applied to complete a synthesis of pamamycin 607 (1). (2S,3R,6S,8R)-1-Benzyloxy-8-[N-methyl-N-(toluene-4- sulfonyl)amino]-3,6-epoxy-2-methylundecane (35) was prepared stereoselectively from (R)-3-[N-(toluene-4-sulfonyl)-N-methylamino]hexanal (32) by reaction with the stannane 3 followed by cyclisation of the resulting alkenol 33 and deselenation. Following debenzylation and oxidation, an aldol reaction of the aldehyde 37 using the lithium enolate of 2,6-dimethylphenyl propanoate (61) gave mainly the 2,3-anti-3,4-syn-adduct 48. After protection of the secondary alcohol as its tert-butyldimethylsilyl ether 49, reduction using DIBAL-H and oxidation, the resulting aldehyde, (2S,3S,4R,5R,8S,10R)-3-tert- butyldimethylsilyloxy-2,4-dimethyl-5,8-epoxy-10-[N-methyl-N-(toluene-4-sulfonyl) amino]tridecanal (62), was taken through to the bis-tetrahydrofuran 65 by repeating the sequence of the reactions with the stannane 3, cyclisation and deselenation. The N-(toluene-4-sulfonyl) group was then replaced by an N-(tert-butoxycarbonyl) group and O-debenzylation and oxidation gave the carboxylic acid 70 that corresponds to the C(1)-C(18) fragment of pamamycin 607 (1). Similar chemistry was used to prepare the C(1′)-C(11′) fragment 89 of the pamamycin, except that in this case the configuration of the secondary alcohol introduced by the allylstannane reaction had to be inverted using a Mitsunobu reaction before the cyclisation. Esterification of the carboxylic acid of the C(1)-C(18)-fragment 70 using the alcohol 89 of the C(1′)-C(11′) fragment followed by selective deprotection, macrocyclisation, N-deprotection and N-methylation gave pamamycin 607 (1) that was identical to a sample of the natural product. The Royal Society of Chemistry 2012.
Total synthesis of Z-isomer of phomolide B
Mohapatra, Debendra K.,Reddy, D. Prabhakar,Dash, Uttam,Yadav
scheme or table, p. 151 - 154 (2011/02/26)
We have achieved the synthesis of Z-isomer of phomolide B during our investigation toward the effect of protecting group on the outcome of ring-closing metathesis reaction. The other key reactions involved are cis-selective partial hydrogenation, Sharples
Formal total synthesis of neopeltolide
Vintonyak, Viktor V.,Maier, Martin E.
supporting information; experimental part, p. 1239 - 1242 (2009/04/12)
A concise synthesis of the core structure of the macrolide neopeltolide was develop featuring a Prins cyclization to fashion the pyran ring. Key steps in the synthesis of aldehyde 16 were a Leiqhton allylation and a Feringa-Minnaard asymmetric methyl cuprate addition to an unsaturated thioester. For lactonization, a classical Yamaguchin macrolactonization was used. The longest linear sequence consists of 17 steps providing lactone 26 with an overall yield of 23%.
