Silyl-biaryl phosphoramidites and methods of making

A compound of Formula Ib:

• wherein:
• R3 and R4 are each ethyl;
• R5 is selected from:
• R6 and R7 are each independently selected from an alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, or heteroaryl group, each of which may be optionally substituted with one or more Rz groups as allowed by valence;
• or R6 and R7 are brought together with the nitrogen to which they are attached to form a heterocycloalkyl, heterocycloalkenyl or heteroaryl ring, each of which may be optionally substituted one or more Rz groups as allowed by valence;
• Ra and Rb are independently selected at each occurrence from a hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, or heteroaryl group, each of which except for hydrogen may be optionally substituted with one or more Rd groups as allowed by valence;
• Rc is independently selected at each occurrence from —Ra, —ORa, or -NRaRb;
• Rd is independently selected at each occurrence from halo, azido, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, heteroaryl, aldehyde, amino, carboxylic acid, ester, ether, halide, hydroxy, ketone, nitro, silyl, sulfo-oxo, sulfonyl, sulfone, sulfoxide, and thiol;
• and
• Ry and Rz are independently selected at each occurrence from halo, nitro, cyano, —Ra, —ORa, —SRa, —NRaRb, —C(O)Rc, —OC(O)Rc, —N(Rb)—C(O)Rc, —S(O)Rc, —OS(O)Rc, —N(Rb)—S(O)Rc, —S(O)2Rc, —OS(O)2Rc, and —N(Rb)—S(O)2Rc.