Propargyltitanium reagents

P-Acetylenic alcohols (11, 378). The propargyltitanium reagent derived from 1-trimethylsilyl-3-(tetrahydropyranyloxy)propyne (1) reacts with crotonaldehydes to afford the P-acetylenic alcohol 2 with high stereoselectivity. This alcohol was used in a stcr-eocontrolled synthesis of the natural antibiotic ( )-asperlin (6). 

In organic synthesis, propargyltitanium(rV) complexes are unique among the organometallic reagents in that they perform efficient addition of either alkynic or allenic residues to carbonyl compounds. 

Since this topic will be covered extensively in Part 1 Volume 2, only the main references concerning their preparation and their more significant synthetic applications are recalled at this point. - Hetero-substituted propargyltitanium(IV) reagents are also very useful in the synthesis of natural products. 

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