Abstmct: A ba.wpromotedcawersicn ofa tidal B@ intoa formyl alkyna andits convmien to a stemidal diyw is deaeribed. @ 1997Published by ElsevierScienceLtd. The enediyne antitumo r antibiotics derived fiombacterial sourceshavegenerated widespread interedd ueto DNA cleavage.However,the chemicaliuatsbility and extremepotencyof these MturanyOccming COIUP* m~ct th~fiomkoad useas m-r agmt.3ASa resultsynthesisof artificial enediyw attraot enormousintereats4,5aimed at greater chemicalstabilityand enhancedsntitmne r eiiicwy. Further, the -1? atmctmd complexitiesof enediynes has temptedorganicchemistsm the search of synthetic strategies involving intram olecularcychaation4~6 of acetylide withnon-enolizable aldehyde group. The synthesis of estramycrn7 has allowedaccess to a new class of enediynes by enclosingthe diene diynemoietywithinthe steroidalcore. Recentlywe haveinitiateda programsm whichwe manipulate the ateroidal D-ring.gThe geminald.ihalides are idealtemplatesl"aa well as importantSubatrateall for a broad rsnge of cmnpounda. In continuation of our rnterestalzto explorethe veraa&y of steroidalC-17 gemiaal dihalid~we wishto reporthereaneiikientone-potsynthesis of a ateroidal ales-Dformyi@ne andhautility forthe synthesis of a novelclassof ateroidal diynes. .c@5?. &~.&' 1 OH-.&c= 'i!i!~' 4 Reagents : i) KOH/MeOH-H20(4:l); ii) Ac20/Pyridine; iii) Propargyl bromide/Zn/THF When 3-*aeetoxy-l7,l7-dicldore-l6(E)-chloromethyleneandr0.9-5-UM 1 waa rduxed m mathanolie KOH aolution(MoOH:H20=4:1) for O.% it underwent ring openingto ailbrdthe ales-DE#emidal _ @no 2 m 70% yield.Acetylation of 2 d ad *Y*