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Enantio- And Diastereoselective Additions to Aldehydes Using the Bifunctional Reagent 2-(chloromethyl)-3-(tributylstannyl)propene: Application to a Synthesis of the C16-C27 Segment of Bryostatin 1

Enantio- And Diastereoselective Additions to Aldehydes Using the Bifunctional Reagent 2-(chloromethyl)-3-(tributylstannyl)propene: Application to a Synthesis of the C16-C27 Segment of Bryostatin 1

Gary E Keck, Tao Yu, Mark D McLaws

J Org Chem. 2005 Apr 1;70(7):2543-50.

PMID: 15787541

Abstract:

[reaction: see text] Reactions of the bifunctional allylstannane 2-(chloromethyl)-3-(tributylstannyl)propene with aldehydes have been examined. These generally occur in high yields using Lewis acid promoters and the products can be isolated and purified without incident. Good yields and high enantioselectivities are also realized in catalytic asymmetric allylations (CAA reactions) using the previously described BITIP catalyst system. Protection of the free hydroxyl can be accomplished without cyclization to the derived tetrahydrofuran, although this transformation is also facile. The utility of the incorporated allyl chloride functionality allows for the obvious use of such products in reactions with nucleophiles. Use of these products in a less obvious connective strategy is demonstrated in the synthesis of the C12-C27 segment of bryostatin 1 where a connective, or "lynchpin", double-allylation process was employed. The beta-hydroxy allyl chloride obtained from an initial chelation-controlled allylation of aldehyde 16 was converted to allylstannane 19 and applied in a second allylation reaction, thus allowing for a highly convergent synthesis of the bryostatin C ring backbone in a stereoselective fashion.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP100073152	2-(Tributylstannyl)propene		100073-15-2	Price
AP1105511656	2-(Tributylstannyl)-3-methoxypyrazine		1105511-65-6	Price

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