For example, the starting β amide, β acid ester, or β thiolcarbonic acid ester can first be reacted with the silylating agent and then reacted with the cyclizing agent, or the starting compound can be added to {TAIL ~ a mixture} of {HEAD ~ the silylating agent} and the cyclizing agent 
For example , the starting β amide , β acid ester , or β thiolcarbonic acid ester can first be reacted with the silylating agent and then reacted with the cyclizing agent , or the starting compound can be added to { TAIL ~ a mixture } of { HEAD ~ the silylating agent } and the cyclizing agent
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH