Propargylic acetals Subject

Early examples of catalytic radical cyclizations were provided by Okabe and coworkers, who subjected 2-bromoethyl propargyl ethers or bromoacetaldehyde propargyl acetals 257 to complex 255 as a catalyst and sodium borohydride as the stoichiometric reducing agent (Fig. 63, Table 5, entry 1) [307, 308]. 

Rzaeva et al." compared propargyl ether, propargyloxy formates, and propar-gyloxy acetates, and found them all to be effective inhibitors of steel in HCI. Allabergenov et al." synthesized various propargyl ethers of substituted phenols, which also proved to be quite effective (18% HCI at 160°F, i.e., 71°C). One such product, 1-phenoxy-2-butyn-4-ol, is so exceptional that it has been the subject of subsequent studies."... 

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