02123nas a2200253   4500008004100000022001400041245009900055210006900154260010600223300001400329490000700343520116100350653003301511653003601544653002201580653002101602653001701623653003101640653001401671100001701685700001801702700001901720856013001739       2005                        eng d  a0040-402000aSynthesis of naturally occurring bioactive butyrolactones: maculalactones A-C and nostoclide I0 aSynthesis of naturally occurring bioactive butyrolactones macula  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAY  a5297-53020 v613 a<p>Starting from citraconic anhydride (13), a simple multistep (9-10 steps) synthesis of naturally occurring butyrolactones maculalactone A (3), maculalactone B (1), maculalactone C (2) and nostoclide 1 (4) have been described with good overall yields via dibenzylmaleic anhydride (20) and benzylisopropylmaleic anhydride (27). The two anhydrides 20 and 27 were prepared by S(N)2' coupling reactions of appropriate Grignard reagents with dimethyl bromomethylfumarate (14), LiOH-induced hydrolysis of esters to acids, bromination of carbon-carbon double bond, in situ dehydration followed by dehydrobromination and chemoselective allylic substitution of bromoatom in disubstituted anhydrides 19 and 26 with appropriate Grignard reagents. The NaBH4 reduction of these anhydrides 20 and 27 furnished the desired lactones 21 and 29, respectively. The lactone 21 on Knoevenagel condensation with benzaldehyde, furnished maculalactone B (1), which on isomerization gave maculalactone C (2). Selective catalytic hydrogenation of 1 gave maculalactone A (3). The conversion of lactone 29 to nostoclide 1 (4) is known. (c) 2005 Elsevier Ltd. All rights reserved.</p>10adimethyl bromomethylfumarate10adisubstituted maleic anhydrides10amaculalactone A-C10aNaBH4 reductions10anostoclide 110aS(N)2 ` Grignard couplings10asynthesis1 aKar, Anirban1 aGogoi, Sanjib1 aArgade, N., P.  uhttps://library.ncl.res.in/content/synthesis-naturally-occurring-bioactive-butyrolactones-maculalactones-c-and-nostoclide-i-0